Don't reject threaded Python on FreeBSD.

According to Chris Rees, this has worked for awhile, and the current
FreeBSD port is removing the test anyway.

config/python.m4

@@ -78,13 +78,13 @@ AC_SUBST(python_libdir)[]dnl
 AC_SUBST(python_libspec)[]dnl
 AC_SUBST(python_additional_libs)[]dnl
 
-# threaded python is not supported on bsd's
+# threaded python is not supported on OpenBSD
 AC_MSG_CHECKING(whether Python is compiled with thread support)
 pythreads=`${PYTHON} -c "import sys; print int('thread' in sys.builtin_module_names)"`
 if test "$pythreads" = "1"; then
   AC_MSG_RESULT(yes)
   case $host_os in
-  openbsd*|freebsd*)
+  openbsd*)
     AC_MSG_ERROR([threaded Python not supported on this platform])
     ;;
   esac

configure

@@ -5504,7 +5504,7 @@ echo "$as_me:$LINENO: result: ${python_libspec} ${python_additional_libs}" >&5
 echo "${ECHO_T}${python_libspec} ${python_additional_libs}" >&6
 
 
-# threaded python is not supported on bsd's
+# threaded python is not supported on OpenBSD
 echo "$as_me:$LINENO: checking whether Python is compiled with thread support" >&5
 echo $ECHO_N "checking whether Python is compiled with thread support... $ECHO_C" >&6
 pythreads=`${PYTHON} -c "import sys; print int('thread' in sys.builtin_module_names)"`
@@ -5512,7 +5512,7 @@ if test "$pythreads" = "1"; then
   echo "$as_me:$LINENO: result: yes" >&5
 echo "${ECHO_T}yes" >&6
   case $host_os in
-  openbsd*|freebsd*)
+  openbsd*)
     { { echo "$as_me:$LINENO: error: threaded Python not supported on this platform" >&5
 echo "$as_me: error: threaded Python not supported on this platform" >&2;}
    { (exit 1); exit 1; }; }