[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>
diff --git a/gn/BUILD.gn b/gn/BUILD.gn
index 64d019e..09efdac 100644
--- a/gn/BUILD.gn
+++ b/gn/BUILD.gn
@@ -18,6 +18,12 @@
   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") {
@@ -63,6 +69,11 @@
       "-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",
     ]
   }
 }