Restore building on old Mac OS X (Darwin) with GCC (re: e74e98b8)

In making ksh build on new macOS, it stopped building on old Mac OS
X (old gcc-based Darwin). There is no real reason for this. We can
just restore the old cc wrapper script and use it if an old gcc
compiler is detected.

This is only tested on Mac OS X 10.3 on my old Power Mac G5 so far.
But at least that allows me to test fixes on that platform. Unusual
platforms sometimes expose corner case bugs...

bin/package, src/cmd/INIT/package.sh:
- If /usr/bin/cc is GCC, change 'darwin' host name to 'darwin_old'.
  This removes the long-obsolete 'darwin7' host name.

src/cmd/INIT/cc.darwin_old:
- Restore the old cc.darwin script for darwin_old hosts.

(cherry picked from commit 93d4c6497ea8e9cc9f4977b75d06a673a2229f80)

bin/package

@@ -2395,8 +2395,8 @@ int main()
 			esac
 			case $lhs in
 			bsdi)			lhs=bsd ;;
-			darwin)			case $rel in
-						[01234567].*)	lhs=${lhs}7 ;;
+			darwin)			case $(/usr/bin/cc --version) in
+						*'(GCC)'*)	lhs=${lhs}_old ;;
 						esac
 						;;
 			freebsd)		case $rel in