[warnings] Add -Wunused-macros

This CL adds the `-Wunused-macros` warning and removes the unused macro
found.

Change-Id: I1b2aa925f89e19ff6184e34b59d5ee076cb3807c
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/89560
Auto-Submit: Dan Sinclair <dsinclair@chromium.org>
Commit-Queue: Corentin Wallez <cwallez@chromium.org>
Reviewed-by: Corentin Wallez <cwallez@chromium.org>

src/dawn/common/BUILD.gn

@@ -121,6 +121,7 @@ config("internal_config") {
       "-Wtautological-unsigned-zero-compare",
       "-Wunreachable-code-aggressive",
       "-Wunused-but-set-variable",
+      "-Wunused-macros",
     ]
 
     if (is_win) {

src/dawn/tests/end2end/NonzeroTextureCreationTests.cpp

@@ -68,9 +68,6 @@ class ExpectNonZero : public detail::CustomTextureExpectation {
     }
 };
 
-#define EXPECT_TEXTURE_NONZERO(T, ...) \
-    AddTextureExpectation(__FILE__, __LINE__, new ExpectNonZero<T>(), __VA_ARGS__)
-
 class NonzeroTextureCreationTests : public DawnTestWithParams<Params> {
   protected:
     constexpr static uint32_t kSize = 128;