Introduce cc_baremetal_defaults

Add a way to easily share configuration across all C/C++ libraries
targeting a "baremetal" environment (typically AArch64 EL1) but
unfortunately re-using the cc infrastructure, which actually targets
Android EL0. This will be used to restrict the compiler flags in a
follow-up.

Note: No functional change intended.

Test: m
Change-Id: I1160d87088090d2f429f33ea53385329e5caa2ce
diff --git a/Android.bp b/Android.bp
index d71bcec..34f9bf0 100644
--- a/Android.bp
+++ b/Android.bp
@@ -142,6 +142,14 @@
     visibility: ["//visibility:public"],
 }
 
+// Defaults to share configs between "baremetal" Soong modules, currently only
+// used for code running in kernel context within Android Virtualization
+// Framework guests.
+cc_defaults {
+    name: "cc_baremetal_defaults",
+    defaults_visibility: ["//visibility:public"],
+}
+
 product_config {
     name: "product_config",
     visibility: [