bug#26638: 25.2; Fatal error 6: Abortmake[1]: *** [Makefile:737: bootstrap-emacs] Abort (core dumped)

[Paul Eggert]

Do you have the same problem when you build it for a 64-bit executable? Try 
'./configure --with-gif=no CFLAGS="-m64 -g3"'.  If that doesn't work, try adding 
-O to CFLAGS.

At this point I'm just trying to get Emacs working for you, as opposed to fixing 
the bug, which is probably in the combination of unexec and malloc. If we can't 
get it working for 25.2 the next thing to try will be to get it working for master.