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

@@ -85,13 +85,13 @@ 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

@@ -7401,7 +7401,7 @@ python_additional_libs=`${PYTHON} -c "import distutils.sysconfig; print(' '.join
 $as_echo "${python_libspec} ${python_additional_libs}" >&6; }
 
 
-# threaded python is not supported on bsd's
+# threaded python is not supported on OpenBSD
 { $as_echo "$as_me:$LINENO: checking whether Python is compiled with thread support" >&5
 $as_echo_n "checking whether Python is compiled with thread support... " >&6; }
 pythreads=`${PYTHON} -c "import sys; print(int('thread' in sys.builtin_module_names))"`
@@ -7409,7 +7409,7 @@ if test "$pythreads" = "1"; then
   { $as_echo "$as_me:$LINENO: result: yes" >&5
 $as_echo "yes" >&6; }
   case $host_os in
-  openbsd*|freebsd*)
+  openbsd*)
     { { $as_echo "$as_me:$LINENO: error: threaded Python not supported on this platform" >&5
 $as_echo "$as_me: error: threaded Python not supported on this platform" >&2;}
    { (exit 1); exit 1; }; }