build: fix GN build for sqlite and nghttp2

PR-URL: #55529
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Cheng Zhao <zcbenz@gmail.com>
Reviewed-By: Yagiz Nizipli <yagiz@nizipli.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>

Author: codebytere

deps/nghttp2/unofficial.gni

@@ -34,6 +34,9 @@ template("nghttp2_gn_build") {
     if (is_clang || !is_win) {
       cflags_c = [
         "-Wno-implicit-fallthrough",
+        # Ref https://github.com/nghttp2/nghttp2/pull/2258
+        # This can be removed when the above PR is ingested.
+        "-Wno-extra-semi",
       ]
     }
   }

deps/sqlite/unofficial.gni

@@ -18,8 +18,14 @@ template("sqlite_gn_build") {
     forward_variables_from(invoker, "*")
     public_configs = [ ":sqlite_config" ]
     sources = gypi_values.sqlite_sources
+    cflags_c = [
+      "-Wno-implicit-fallthrough",
+      "-Wno-unreachable-code-return",
+      "-Wno-unreachable-code-break",
+      "-Wno-unreachable-code",
+    ]
     if (is_win) {
-      cflags_c = [
+      cflags_c += [
         "-Wno-sign-compare",
         "-Wno-unused-but-set-variable",
         "-Wno-unused-function",