runtime/cgo: update comments

Change-Id: Ib5356181c3204c8f9922eeb4da1c06bfdb18f443
Reviewed-on: https://go-review.googlesource.com/54812Reviewed-by: Ian Lance Taylor <iant@golang.org>

src/runtime/cgo/gcc_darwin_386.c

@@ -39,8 +39,8 @@ inittls(void)
 	 *
 	 * The linker and runtime hard-code this constant offset
 	 * from %gs where we expect to find g.
-	 * Known to ../../../liblink/sym.c:/468
-	 * and to ../sys_darwin_386.s:/468
+	 * Known to src/cmd/link/internal/ld/sym.go:/0x468
+	 * and to src/runtime/sys_darwin_386.s:/0x468
 	 *
 	 * This is truly disgusting and a bit fragile, but taking care
 	 * of it here protects the rest of the system from damage.

src/runtime/cgo/gcc_darwin_amd64.c

@@ -28,8 +28,8 @@ inittls(void)
 	 *
 	 * The linker and runtime hard-code this constant offset
 	 * from %gs where we expect to find g.
-	 * Known to ../../../liblink/sym.c:/8a0
-	 * and to ../sys_darwin_amd64.s:/8a0
+	 * Known to src/cmd/link/internal/ld/sym.go:/0x8a0
+	 * and to src/runtime/sys_darwin_amd64.s:/0x8a0
 	 *
 	 * As disgusting as on the 386; same justification.
 	 */