1. On AIX, AC_LBL_C_INLINE detected the compiler supported
the inline keyword which is wrong. AC_C_INLINE from
autoconf-2.59 worked.
2. AC_CHECK_TYPE from autoconf-2.5x is no longer broken.
Replaced AC_LBL_CHECK_TYPE with it, mainly to use
<sys/bitypes.h> for Tru64 UNIX where some of the u_int#_t
types are defined.
3. Tru64 UNIX 4.0D doesn't support %llx; however, it does support %lx.
4. Added <stdint.h> to interface.h for int#_t types on
Tru64 UNIX 4.0D (required for missing/snprintf.c).
5. Reworked includes in tcpdump-stdinc.h for int#_t types.