Introduce avf_build_flags_cc cc_defaults

These are similar to avf_build_rust_build flags, but for cc_* soong
modules.

In the immediate future this will be used for flag guarding
virtcpu-freq related changes to platform.dts.

This patch also adds avf_build_flags_cc as cc_defaults to all our
existing cc_* soong modules

Test: builds
Bug: 284369518
Change-Id: I19152675802548cd9efba30a40bccdbb14867fe1
diff --git a/microdroid/kdump/Android.bp b/microdroid/kdump/Android.bp
index ff73fdb..5d129f4 100644
--- a/microdroid/kdump/Android.bp
+++ b/microdroid/kdump/Android.bp
@@ -5,6 +5,7 @@
 
 cc_binary {
     name: "microdroid_kexec",
+    defaults: ["avf_build_flags_cc"],
     stem: "kexec_load",
     srcs: ["kexec.c"],
     installable: false,
@@ -14,6 +15,7 @@
 
 cc_binary {
     name: "microdroid_crashdump",
+    defaults: ["avf_build_flags_cc"],
     stem: "crashdump",
     srcs: ["crashdump.c"],
     static_executable: true,