bug#32927: 27.0.50; libxml not found when building on macOS Mojave

[Philipp <p.stephani2@gmail.com>]

Currently 'make' fails for me on master due to:

$ make V=1
/Applications/Xcode.app/Contents/Developer/usr/bin/make -C lib all
make[1]: Nothing to be done for `all'.
/Applications/Xcode.app/Contents/Developer/usr/bin/make -C lib-src all
make[1]: Nothing to be done for `all'.
/Applications/Xcode.app/Contents/Developer/usr/bin/make -C src VCSWITNESS='$(srcdir)/../.git/logs/HEAD' all
gcc -c  -Demacs  -I. -I. -I../lib -I../lib   -isystem /usr/X11/include    -DMAGICKCORE_HDRI_ENABLE=1 -DMAGICKCORE_QUANTUM_DEPTH=16 -DMAGICKCORE_HDRI_ENABLE=1 -DMAGICKCORE_QUANTUM_DEPTH=16 -isystem /usr/local/Cellar/imagemagick/7.0.8-12/include/ImageMagick-7  -isystem /usr/include/libxml2       -isystem /usr/local/Cellar/little-cms2/2.9/include      -MMD -MF deps/xml.d -MP  -isystem /usr/local/Cellar/jansson/2.11/include -isystem /usr/local/Cellar/gnutls/3.5.19/include -isystem /usr/local/Cellar/nettle/3.4/include -isystem /usr/local/Cellar/libtasn1/4.13/include -isystem /usr/local/Cellar/p11-kit/0.23.14/include/p11-kit-1   -Werror -fno-common -W -Waddress -Wall -Wattributes -Wbuiltin-macro-redefined -Wchar-subscripts -Wcomment -Wcomments -Wcpp -Wdangling-else -Wdate-time -Wdeprecated -Wdeprecated-declarations -Wdisabled-optimization -Wdiv-by-zero -Wduplicate-decl-specifier -Wempty-body -Wendif-labels -Wenum-compare -Wexpansion-to-defined -Wextra -Wformat-extra-args -Wformat-security -Wformat-y2k -Wformat-zero-length -Wignored-attributes -Wignored-qualifiers -Wimplicit -Wimplicit-function-declaration -Wimplicit-int -Wincompatible-pointer-types -Winit-self -Wint-conversion -Wint-to-pointer-cast -Winvalid-pch -Wlogical-not-parentheses -Wmain -Wmissing-declarations -Wmissing-include-dirs -Wmissing-prototypes -Wmultichar -Wnarrowing -Wnested-externs -Wnonnull -Wnull-dereference -Wodr -Wold-style-definition -Woverflow -Wpacked -Wparentheses -Wpointer-arith -Wpointer-sign -Wpointer-to-int-cast -Wpragmas -Wreturn-type -Wsequence-point -Wshift-count-negative -Wshift-count-overflow -Wshift-negative-value -Wsizeof-array-argument -Wsizeof-pointer-memaccess -Wstrict-aliasing -Wstrict-prototypes -Wswitch-bool -Wtautological-compare -Wtrigraphs -Wuninitialized -Wunknown-pragmas -Wunused -Wunused-function -Wunused-label -Wunused-local-typedefs -Wunused-result -Wunused-value -Wunused-variable -Wvarargs -Wvariadic-macros -Wvolatile-register-var -Wwrite-strings -Wredundant-decls -Wno-missing-field-initializers -Wno-sign-compare -Wno-type-limits -Wno-unused-parameter -Wno-format-nonliteral -Wno-missing-braces -Wno-initializer-overrides -Wno-tautological-compare -Wno-tautological-constant-out-of-range-compare -ggdb3 -O0 -Wno-error=null-pointer-arithmetic  xml.c
xml.c:26:10: fatal error: 'libxml/tree.h' file not found
#include <libxml/tree.h>
         ^~~~~~~~~~~~~~~
1 error generated.
make[1]: *** [xml.o] Error 1
make: *** [src] Error 2

$ ./config.status --config
'--with-modules' '--without-pop' '--with-mailutils' '--enable-gcc-warnings=yes' '--enable-checking=all' '--enable-check-lisp-object-type' 'CFLAGS=-ggdb3 -O0 -Wno-error=null-pointer-arithmetic'

This is on macOS Mojave with Xcode 10.0.


In GNU Emacs 27.0.50 (build 17, x86_64-apple-darwin17.4.0, NS appkit-1561.20 Version 10.13.3 (Build 17D102))
 of 2018-09-21
Repository revision: ee3be3fdfa96d7d1a0740c8145a26d758c12a711
Windowing system distributor 'Apple', version 10.3.1671
System Description:  Mac OS X 10.14

Recent messages:
For information about GNU Emacs and the GNU system, type C-h C-a.

Configured using:
 'configure --with-modules --without-pop --with-mailutils
 --enable-gcc-warnings=yes --enable-checking
 --enable-check-lisp-object-type 'CFLAGS=-ggdb3 -O0''

Configured features:
IMAGEMAGICK NOTIFY ACL GNUTLS LIBXML2 ZLIB TOOLKIT_SCROLL_BARS NS
MODULES THREADS JSON LCMS2 GMP

Important settings:
  value of $LANG: de_DE.UTF-8
  locale-coding-system: utf-8-unix

Major mode: Lisp Interaction

Minor modes in effect:
  tooltip-mode: t
  global-eldoc-mode: t
  eldoc-mode: t
  electric-indent-mode: t
  mouse-wheel-mode: t
  tool-bar-mode: t
  menu-bar-mode: t
  file-name-shadow-mode: t
  global-font-lock-mode: t
  font-lock-mode: t
  blink-cursor-mode: t
  auto-composition-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t
  line-number-mode: t
  transient-mark-mode: t

Load-path shadows:
None found.

Features:
(shadow sort mail-extr emacsbug message rmc dired dired-loaddefs
format-spec rfc822 mml easymenu mml-sec epa derived epg epg-config
gnus-util rmail rmail-loaddefs mm-decode mm-bodies mm-encode mail-parse
rfc2231 mailabbrev gmm-utils mailheader sendmail rfc2047 rfc2045
ietf-drums mm-util mail-prsvr mail-utils phst pcase ffap thingatpt
url-parse auth-source cl-seq eieio eieio-core cl-macs eieio-loaddefs
password-cache json map url-vars subr-x rx gnutls puny seq byte-opt gv
bytecomp byte-compile cconv dbus xml cl-loaddefs cl-lib elec-pair
time-date tooltip eldoc electric uniquify ediff-hook vc-hooks
lisp-float-type mwheel term/ns-win ns-win ucs-normalize mule-util
term/common-win tool-bar dnd fontset image regexp-opt fringe
tabulated-list replace newcomment text-mode elisp-mode lisp-mode
prog-mode register page menu-bar rfn-eshadow isearch timer select
scroll-bar mouse jit-lock font-lock syntax facemenu font-core
term/tty-colors frame cl-generic cham georgian utf-8-lang misc-lang
vietnamese tibetan thai tai-viet lao korean japanese eucjp-ms cp51932
hebrew greek romanian slovak czech european ethiopic indian cyrillic
chinese composite charscript charprop case-table epa-hook jka-cmpr-hook
help simple abbrev obarray minibuffer cl-preloaded nadvice loaddefs
button faces cus-face macroexp files text-properties overlay sha1 md5
base64 format env code-pages mule custom widget hashtable-print-readable
backquote threads kqueue cocoa ns lcms2 multi-tty make-network-process
emacs)

Memory information:
((conses 16 217251 7421)
 (symbols 48 21677 1)
 (strings 32 33393 2133)
 (string-bytes 1 904721)
 (vectors 16 37435)
 (vector-slots 8 753280 13522)
 (floats 8 50 66)
 (intervals 56 218 0)
 (buffers 992 11))