Cygwin allows applications to supply their own malloc but not, until
today, their own posix_memalign. This has caused problems with the GTK
build of Emacs on Cygwin. The problem became worse with the latest Glib
update. Anyone who wants the gory details can find them starting here:
http://cygwin.com/ml/cygwin-xfree/2013-08/msg00018.html
Cygwin was just patched today to allow applications to supply their own
posix_memalign (but not their own memalign), which solves the Glib
problem. But posix_memalign in gmalloc.c calls memalign, so I need to
make sure that it calls Emacs's memalign. The attached patch does this.
Is this a reasonable way to handle the problem? (I plan to also add
an explanatory comment.)