bug#18383: Build failure

[Angelo Graziosi <angelo.graziosi@alice.it>]

Current trun, rev. 117801, fails to build (I tried on MSYS2-MinGW64) 
with this compiler error:

gcc -std=gnu99  -c -mtune=generic   -DUSE_CRT_DLL=1 -I /tmp/emacs/nt/inc 
-Demacs  -I. -I. -I../lib -I../lib  -mtune=generic 
-IC:/msys64/mingw64/include/librsvg-2.0 
-IC:/msys64/mingw64/include/gdk-pixbuf-2.0 -pthread 
-IC:/msys64/mingw64/include/cairo -IC:/msys64/mingw64/include/glib-2.0 
-IC:/msys64/mingw64/lib/glib-2.0/include -mms-bitfields 
-IC:/msys64/mingw64/include/pixman-1 -I/mingw64/include/libpng16 
-I/mingw64/include/harfbuzz  -IC:/msys64/mingw64/include 
-I/mingw64/include/freetype2 -IC:/msys64/mingw64/include/libpng16 
-IC:/msys64/mingw64/include/libxml2 
-IC:/msys64/mingw64/include/dbus-1.0 
-IC:/msys64/mingw64/lib/dbus-1.0/include           -MMD -MF 
deps/fileio.d -MP -IC:/msys64/mingw64/include/p11-kit-1 
-IC:/msys64/mingw64/include      -I/mingw64/include/noX -Ofast -g0 -pipe 
  fileio.c
fileio.c: In function 'Fexpand_file_name':
fileio.c:1345:26: error: 'aidr' undeclared (first use in this function)
       newdirlen = strlen (aidr);
                           ^
fileio.c:1345:26: note: each undeclared identifier is reported only once 
for each function it appears in


maybe this change was the origin of failure:

2014-09-01  Dmitry Antipov  <xyz@xyz>

	Avoid extra calls to strlen in filesystem I/O routines.
	* fileio.c (Fexpand_file_name): Avoid calls to strlen if
	the length of 'newdir' is known or may be precalculated.
	(file_accessible_directory_p): Prefer to pass Lisp_Object,
	not 'char *', and so use precalculated length.
	(Ffile_accessible_directory_p):
	[...]


Ciao,
  Angelo.