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/rs.go b/cc/rs.go
index 5951edb..61fd1a8 100644
--- a/cc/rs.go
+++ b/cc/rs.go
@@ -123,7 +123,7 @@
 	rootRsIncludeDirs := android.PathsForSource(ctx, properties.Renderscript.Include_dirs)
 	flags.rsFlags = append(flags.rsFlags, includeDirsToFlags(rootRsIncludeDirs))
 
-	flags.GlobalFlags = append(flags.GlobalFlags,
+	flags.Local.CommonFlags = append(flags.Local.CommonFlags,
 		"-I"+android.PathForModuleGen(ctx, "rs").String(),
 		"-Iframeworks/rs",
 		"-Iframeworks/rs/cpp",