This patch contributed by John Kodumal.  To use it:

  $ cd smbase
  $ patch <freebsd.regex.patch

Index: smregexp.cc
===================================================================
RCS file: /home/cvs-repository/smbase/smregexp.cc,v
retrieving revision 1.1
diff -u -r1.1 smregexp.cc
--- smregexp.cc 10 Apr 2003 04:00:07 -0000      1.1
+++ smregexp.cc 16 Feb 2004 19:34:49 -0000
@@ -8,8 +8,11 @@
 // for now, I implement everything using the libc POSIX regex
 // facilities
 #include <stddef.h>       // size_t
-#include <regex.h>        // POSIX regex functions
-
+#ifndef __FreeBSD__
+#include <regex.h>
+#else
+#include <gnuregex.h>        // POSIX regex functions
+#endif
 
 // get an error string
 static string regexpErrorString(regex_t const *pat, int code)