Split local and global cflags

Native compiler flags are currently applied in approximately:
global cflags
local cflags
local include dirs
global include dirs
global conlyflags
local conlyflags
global cppflags
local cppflags

This means that a flag that is enabled in the global cppflags
cannot be disabled in the local cflags, and an Android.bp author
must know to disable it in the local cppflags.  A better order
would be:
global cflags
global conlyflags
global cppflags
local cflags
local conlyflags
local cppflags
local include dirs
global include dirs

We are mixing both the global and local cflags into a single
variable, and similar for conlyflags and cppflags, which
prevents reordering them.  This CL prepares to reorder them
by splitting the global and local cflags into separate variables.

Bug: 143713277
Test: m native
Change-Id: Ic55a8c3516c331dc5f2af9d00e59ceca9d3e6c15
diff --git a/cc/proto.go b/cc/proto.go
index f818edc..ae988ec 100644
--- a/cc/proto.go
+++ b/cc/proto.go
@@ -114,13 +114,13 @@
 }
 
 func protoFlags(ctx ModuleContext, flags Flags, p *android.ProtoProperties) Flags {
-	flags.CFlags = append(flags.CFlags, "-DGOOGLE_PROTOBUF_NO_RTTI")
+	flags.Local.CFlags = append(flags.Local.CFlags, "-DGOOGLE_PROTOBUF_NO_RTTI")
 
 	flags.proto = android.GetProtoFlags(ctx, p)
 	if flags.proto.CanonicalPathFromRoot {
-		flags.GlobalFlags = append(flags.GlobalFlags, "-I"+flags.proto.SubDir.String())
+		flags.Local.CommonFlags = append(flags.Local.CommonFlags, "-I"+flags.proto.SubDir.String())
 	}
-	flags.GlobalFlags = append(flags.GlobalFlags, "-I"+flags.proto.Dir.String())
+	flags.Local.CommonFlags = append(flags.Local.CommonFlags, "-I"+flags.proto.Dir.String())
 
 	if String(p.Proto.Plugin) == "" {
 		var plugin string