(Hopefully) fix some issues with older version of autotools

platform/unix/automagic

@@ -18,7 +18,7 @@ AUTOMAKE=$(which automake)
 [[ -x ${AUTOMAKE} ]]   || die "Could not find automake."
 
 automagic() {
-	cp platform/unix/configure.in .
+	cp platform/unix/configure.ac .
 	cp platform/unix/Makefile.am .
 
 	if ! sh platform/unix/gen-makefile; then

platform/unix/configure.ac

@@ -6,7 +6,7 @@ AC_CONFIG_SRCDIR([src/love.cpp])
 AM_INIT_AUTOMAKE([foreign -Wall foreign tar-ustar silent-rules])
 AM_SILENT_RULES
 AC_PREFIX_DEFAULT([/usr])
-AM_PROG_AR
+m4_ifdef([AM_PROG_AR], [AM_PROG_AR])
 AC_PROG_LIBTOOL
 AC_PROG_CC
 AC_PROG_CXX