When building libgpg-error-1.18 with gcc-5.0.0 snapshot, the build will fail
because of the changes in the C preprocessor listed at [1].

The quick fix is to use CPPFLAGS="-P" as described in the link below. See also [2].

[1] https://gcc.gnu.org/gcc-5/porting_to.html
[2] https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65713