The serial 7 of m4macros/ax_gcc_func_attribute.m4 has an issue that when
Wstrict-prototypes is used with gcc, the attribute detection always
fails even if the attribute is actually supported. In such case the fish
cache will never be constructed. It's fixed in serial 12 of the macro in
autoconf-archive and this change updates the one distributed with GIMP
to serial 12.
Commit e64e61ca58 requires the
AX_GCC_FUNC_ATTRIBUTE macro, which requires autoconf-archive, and
might be too new for some distros we want to support. Distribute
it ourselves.
Also, some fixes to the makefile and acinclude.m4