Fix build error when libintl is installed

When building m4-1.4.18b on OpenBSD 6.9, with GNU gettext installed, there is a link error: CCLD test-posix_spawn-chdir ld: error: undefined symbol: libintl_gettext >>> referenced by xalloc-die.c:34 (../../lib/xalloc-die.c:34) >>> xalloc-die.o:(xalloc_die) in archive ../lib/lib

free tests: Avoid test failure on glibc < 2.15

When building m4-1.4.18b on a glibc 2.13 system, there is a test failure: test-free: malloc.c:3551: munmap_chunk: Assertion `ret == 0' failed. Aborted This is an internal assertion that was fixed in glibc ([BZ #13276]) on 2011-10-29, that is, before glibc 2.15. Let's avoid this failure, since we

test failure on Haiku

On Haiku (32-bit), compiling m4-1.4.18b+fixes works fine, but one of the tests fails: -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= Checking ../../checks/198.sysval @ ../doc/m4.texi:6749: Origin of test ../../checks/198.sysval: stdout mismatch --- m4-tmp.10743/m4-xout