Revert "[spirv] Suppress new warning in HEAD clang."

This reverts commit 3e4ec3c8e66b6cc4a0bec238fa639c85f0466887.

Reason for revert: Breaks roll.

Strangely, it looks like this pattern doesn't appear to have worked since 2011, even though I got it out of our team's docs. Reverting until I figure out what to do here.

Original change's description:
> [spirv] Suppress new warning in HEAD clang.
>
> Head clang introduces a -Wunqualified-std-cast-call, which trips on this
> project. This change disables this warning, and should be reverted once
> upstream is fixed and merged.
>
> Bug: 94668
> Bug: 94519
>
> Change-Id: I68969a57ff05c5708559895ed7273136f63fb20d
> Reviewed-on: https://fuchsia-review.googlesource.com/c/third_party/spirv-cross/+/652423
> Reviewed-by: Chris Fontas <cfontas@google.com>
> Reviewed-by: Yilong Li <liyl@google.com>

Bug: 94668
Bug: 94519
Change-Id: I61b6aac76816cf45fcc97c3a929859899c210d6b
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://fuchsia-review.googlesource.com/c/third_party/spirv-cross/+/652925
Reviewed-by: RubberStamper 🤖 <android-build-ayeaye@system.gserviceaccount.com>
diff --git a/gn/BUILD.gn b/gn/BUILD.gn
index 09efdac..64d019e 100644
--- a/gn/BUILD.gn
+++ b/gn/BUILD.gn
@@ -18,12 +18,6 @@
   include_dirs = [ ".." ]
 
   defines = [ "SPIRV_CROSS_EXCEPTIONS_TO_ASSERTIONS" ]
-  cflags_cc = [
-    # TODO(fxbug.dev/94668)
-    "-Wno-unknown-warning-option",
-    "-Wno-unqualified-std-cast-call",
-    "-Wunknown-warning-option",
-  ]
 }
 
 source_set("spirv_cross_sources") {
@@ -69,11 +63,6 @@
       "-Wno-newline-eof",
       "-Wno-sign-compare",
       "-Wno-unused-variable",
-
-      # TODO(fxbug.dev/94668)
-      "-Wno-unknown-warning-option",
-      "-Wno-unqualified-std-cast-call",
-      "-Wunknown-warning-option",
     ]
   }
 }