Fix BeOS, FreeBSD, MacOS porting problems reported by Bruno Haible.

Fix BeOS, FreeBSD, MacOS porting problems reported by Bruno Haible.
* lib/bitset.c (bitset_print): Don't assume size_t can be printed
with %d format.
* lib/ebitset.c (min, max): Undef before defining.
* lib/vbitset.c (min, max): Likewise.
* lib/subpipe.c (create_subpipe): Save local variables in case
vfork clobbers them.
* tests/synclines.at (AT_SYNCLINES_COMPILE): Add support for the
error message syntax used by gcc-4.0.