build: Fix for internal secmem.
* acinclude.m4 (GNUPG_CHECK_TYPEDEF): Remove. (GNUPG_CHECK_MLOCK): Update from libgcrypt. * configure.ac: Use AC_CHECK_TYPES for byte, ulong, and u64. * secmem/secmem.c: Use HAVE_U64.
- Signed-off-by: NIIBE Yutaka <gniibe@fsij.org>