Updating FreeBSD port

[Mikhail Teterin]

Hello!

In preparing an update of the FreeBSD port of m4 (currently at the 1.4.4) to 
1.4.6, I noticed the following minor nits:

        . Although FreeBSD's getopt.h is detected as sufficiently capable
          by configure, the getopt.c and getopt1.c are still compiled and
          linked into m4, instead of relying on the libc's versions

        . FreeBSD's -lgnuregex is ignored, requiring an explicit
          `--without-included-regex' and minor patching to src/Makefile.in
          to add -lgnuregex to LIBS

        . mkstemp_safer appears to be redundant -- how can mkstemp possibly
          return the STDIN_FILENO?

        . Although *snprintf code is compiled and linked into libm4, none of
          these functions make it into the m4 executable -- are the files
          obsolete?

        . The comment in strcase.m4 states, that no existing system provides
          multi-byte correct strcasecmp -- is there a test one can run to check
          a particular system? If I were to patch m4 to use the libc's 
strcasecmp,
          would running `gmake check' detect a problem, if there were one?

Any comment? Thank you very much!

        -mi