release number bumped to 8.0.12 by export.pike
release number bumped to 8.0.13 by export.pike
Hilfe: Reference correct variable name in guard
Stdio: Fix linking issues with static libgmp.

Linking of Pike failed with "undefined reference to `__gmpz_import'"
when libgmp was a static library (due to the Gmp module being linked
into the pike binary before the _Stdio module).

This fixes the issue by also linking _Stdio with libgmp.
Stdio: Fix compilation issues on OSes without dirfd(3C).

Some operating systems (like eg Solaris 10) do not have dirfd(3C).
Fallback to indexing the DIR with dd_fd or d_fd to get the fd.
release number bumped to 8.0.14 by export.pike
release number bumped to 8.0.15 by export.pike
Changed cast in Gmp.mpz from private to protected.
Added minimal argument checking to cast()
Build: Improved support for --disable-binary.

Don't attempt to make depend in post_modules when cross-compiling
or --disable-binary, since a fresh pike is needed to generate the
sources there.

Fixes issues with source dists generated with --disable-binary
and an old system pike, where broken files would show up in
the resulting archive and not be regenerated on actual build.