Change core.json to add port/ and amd64/ to the include path.

I forget why, but there is a feeling that relative includes are "bad"

Change-Id: I9607a7bff35d70c3c4c61c5a1a7bf8e1981b257a
Signed-off-by: Ronald G. Minnich <rminnich@gmail.com>

sys/src/9/amd64/core.json

@@ -19,7 +19,10 @@
 			"-Wno-unused-parameter",
 			"-Wno-missing-braces",
 			"-Wno-parentheses",
-			"-Wno-unknown-pragmas"
+			"-Wno-unknown-pragmas",
+			"-Werror",
+			"-I", "/sys/src/9/amd64",
+			"-I", "/sys/src/9/port"
 		],
 		"Libs": [
 			"/amd64/lib/klibmemlayer.a",