Reland "Consistently prepend arch-specific headers"

This reverts commit cacb972dcda2ee9e537af467f04f1e8cb1b7cb4f.

Relanding along with one more fix in prebuilts/ndk

Change-Id: I65cbc3c5d72bb47bd00e123c63911c9baa1e5f03
Test: m checkbuild
diff --git a/cc/library.go b/cc/library.go
index 93bd56c..196d575 100644
--- a/cc/library.go
+++ b/cc/library.go
@@ -183,11 +183,11 @@
 	// be added to the include path (using -I) for this module and any module that links
 	// against this module.  Directories listed in export_include_dirs do not need to be
 	// listed in local_include_dirs.
-	Export_include_dirs []string `android:"arch_variant"`
+	Export_include_dirs []string `android:"arch_variant,variant_prepend"`
 
 	// list of directories that will be added to the system include path
 	// using -isystem for this module and any module that links against this module.
-	Export_system_include_dirs []string `android:"arch_variant"`
+	Export_system_include_dirs []string `android:"arch_variant,variant_prepend"`
 
 	Target struct {
 		Vendor, Product struct {