Suppress nonportable include path warning.

src/tests/BUILD.gn

@@ -615,6 +615,9 @@ if (build_angle_deqp_tests && !is_fuchsia) {
         "-Wno-string-conversion",  # implicit conversion turns string literal into bool
         "-Wno-unused-local-typedef",
         "-Wno-unused-result",  # ignoring return value of function declared with 'nodiscard' attribute
+
+        # Suppress a spurious header warning. http://crbug.com/995046
+        "-Wno-nonportable-include-path",
       ]
     }