xcompile: support being called from payloads/external/.../.../

Change-Id: Icc1361fdd3a8369c4b442ce5b8807c549519c93a
Signed-off-by: Stefan Reinauer <stefan.reinauer@coreboot.org>
Reviewed-on: https://review.coreboot.org/14387
Tested-by: build bot (Jenkins)
Reviewed-by: Patrick Georgi <pgeorgi@google.com>

util/xcompile/xcompile

@@ -27,6 +27,12 @@ fi
 TMPFILE=""
 XGCCPATH=$1
 
+# payloads under payloads/external crossgcc path
+if [ -d "$(pwd)/../../../../util/crossgcc/xgcc/bin/" ]
+then
+	XGCCPATH=${XGCCPATH:-"$(pwd)/../../../../util/crossgcc/xgcc/bin/"}
+fi
+
 # libpayload crossgcc path
 if [ -d "$(pwd)/../../util/crossgcc/xgcc/bin/" ]
 then