(jm_CHECK_ALL_TYPES): Require most macros.

(jm_CHECK_ALL_TYPES): Require most macros.
Remove explicit use of AC_HEADER_TIME.  It is required by
jm_CHECK_TYPE_STRUCT_TIMESPEC.  Using AC_HEADER_TIME and
`AC_REQUIRE'ing jm_CHECK_TYPE_STRUCT_TIMESPEC provoked a but
in autoconf whereby the expansion of the latter ended up preceding
the expansion of its prerequisite, AC_HEADER_TIME.
Reported by Volker Borchert.