On this platform, <sys/types.h> does not define off_t if neither
_LP64 nor _FILE_OFFSET_BITS is defined, which can happen if we
#undef _FILE_OFFSET_BITS. This became a problem with the new way
of doing stdbool, since config.h now includes <stdbool.h>, and
Solaris 10 <stdbool.h> includes <sys/feature_tests.h> which
arranges for _FILE_OFFSET_BITS to always be defined (if only to 32),
which <sys/types.h> assumes.
* lib/stackvma.c, lib/vma-iter.c (_FILE_OFFSET_BITS) [__sun && !_LP64]:
Define to 32 instead of leaving undefined.