Bootstrap failure using 'make -j4' [Cygwin]

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

Today, trying to bootstrap Emacs trunk (rev. 100406), using 'make -j4', 
fails always in the same manner:

[...]
gcc -c  -Demacs -DHAVE_CONFIG_H  -I. -I/tmp/emacs/src 
-I/usr/include/gtk-2.0 -I/usr/lib/gtk-2.0/include -I/usr/include/atk-1.0 
-I/usr/include/cairo -I/usr/include/pango-1.0 -I/usr/include/glib-2.0 
-I/usr/lib/glib-2.0/include -I/usr/include/pixman-1 
-I/usr/include/freetype2 -I/usr/include/libpng12 
-I/usr/include/freetype2     -I/usr/include/librsvg-2 
-I/usr/include/glib-2.0 -I/usr/lib/glib-2.0/include 
-I/usr/include/gtk-2.0 -I/usr/include/cairo -I/usr/include/pixman-1 
-I/usr/include/freetype2 -I/usr/include/libpng12 
-I/usr/include/dbus-1.0 -I/usr/lib/dbus-1.0/include   -DORBIT2=1 
-D_REENTRANT -I/usr/include/gconf/2 -I/usr/include/orbit-2.0 
-I/usr/include/dbus-1.0 -I/usr/lib/dbus-1.0/include 
-I/usr/include/glib-2.0 -I/usr/lib/glib-2.0/include   -g -O2 
-Wdeclaration-after-statement -Wno-pointer-sign       -MMD -MF 
deps/frame.d /tmp/emacs/src/frame.c
make[2]: *** [dispnew.o] Error 1
make[2]: *** Waiting for unfinished jobs....
make[2]: Leaving directory `/tmp/emacs/build/src'
make[3]: Leaving directory `/tmp/emacs/build/doc/lispref'
make[1]: *** [src] Error 2
make[1]: *** Waiting for unfinished jobs....
(cd doc/lispintro; /usr/bin/make -w --jobserver-fds=3,4 - 
--jobserver-fds=3,4 - --jobserver-fds=3,4 - --jobserver-fds=3,4 -j info)
make[3]: Entering directory `/tmp/emacs/build/doc/lispintro'
cd /tmp/emacs/doc/lispintro; makeinfo emacs-lisp-intro.texi -o 
../../info/eintr
make[3]: Leaving directory `/tmp/emacs/build/doc/lispintro'
make[2]: Leaving directory `/tmp/emacs/build'
make[1]: Leaving directory `/tmp/emacs/build'
make: *** [bootstrap] Error 2

This happens for the GTK build on Cygwin.

I have done many tries... It looks as if, with 'make -j4', it avoids to 
compile dispnew.c. Indeed I obtain

$ grep dispnew build-emacs-gtk-24.0.50-r100405.log
make[2]: *** [dispnew.o] Error 1

Today I can bootstrap only using 'make -j2' :(

Ciao,
Angelo.