[grpc] Remove unnecessary compiler exceptions/flags

Bug: 1152807
Test: Manual build and run on linux.
Change-Id: I8b82206d47995aa1b90e3196774535de8a0be9e3
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2560061Reviewed-by: Daniel Nicoara <dnicoara@chromium.org>
Reviewed-by: Nico Weber <thakis@chromium.org>
Commit-Queue: Andres Medina <medinaandres@chromium.org>
Auto-Submit: Andres Medina <medinaandres@chromium.org>
Cr-Commit-Position: refs/heads/master@{#831167}

third_party/grpc/BUILD.gn

@@ -65,14 +65,11 @@ config("grpc_config") {
 
 config("grpc_config_private") {
   cflags = [
-    "-Wno-implicit-fallthrough",
-    "-std=c99",
-    "-Wno-sign-compare",
-    "-Wno-unreachable-code",
+    "-Wno-c++98-compat-extra-semi",
     "-Wno-extra-semi",
-    "-Wno-macro-redefined",
-    "-Wno-ignored-qualifiers",
+    "-Wno-sign-compare",
     "-Wno-string-concatenation",
+    "-Wno-unreachable-code",
   ]
 }
 

third_party/grpc/template/BUILD.chromium.gn.template

@@ -70,14 +70,11 @@
 
   config("grpc_config_private") {
     cflags = [
-      "-Wno-implicit-fallthrough",
-      "-std=c99",
-      "-Wno-sign-compare",
-      "-Wno-unreachable-code",
+      "-Wno-c++98-compat-extra-semi",
       "-Wno-extra-semi",
-      "-Wno-macro-redefined",
-      "-Wno-ignored-qualifiers",
+      "-Wno-sign-compare",
       "-Wno-string-concatenation",
+      "-Wno-unreachable-code",
     ]
   }