[dev-only/non-production] Fix GCC build

Move some C++ only flags to cflags_cc.
Doesn't have any effect on in-tree Android
builds.

Bug: 76169489
Change-Id: I597529669913f35d4e1616630940fdc29517629f
diff --git a/gn/standalone/BUILD.gn b/gn/standalone/BUILD.gn
index 7c8d470..bb168e3 100644
--- a/gn/standalone/BUILD.gn
+++ b/gn/standalone/BUILD.gn
@@ -36,11 +36,11 @@
 }
 
 config("no_exceptions") {
-  cflags = [ "-fno-exceptions" ]
+  cflags_cc = [ "-fno-exceptions" ]
 }
 
 config("no_rtti") {
-  cflags = [ "-fno-rtti" ]
+  cflags_cc = [ "-fno-rtti" ]
 }
 
 config("visibility_hidden") {