Recovery variants are built with -D__ANDROID_RECOVERY__

Recovery variant of a module is now by default built with
-D__ANDROID_RECOVERY__, thus eliminating the need to define a custom
macro to conditionally compile the module for the recovery mode.
(Of course, they can define their own macro if needed)

Bug: 63673171
Test: m -j
Change-Id: I1d1b990329793472b93c2f56080e72d690eef9ec

cc/compiler.go

@@ -332,6 +332,10 @@ func (compiler *baseCompiler) compilerFlags(ctx ModuleContext, flags Flags, deps
 			"-D__ANDROID_API__="+version, "-D__ANDROID_VNDK__")
 	}
 
+	if ctx.inRecovery() {
+		flags.GlobalFlags = append(flags.GlobalFlags, "-D__ANDROID_RECOVERY__")
+	}
+
 	instructionSet := String(compiler.Properties.Instruction_set)
 	if flags.RequiredInstructionSet != "" {
 		instructionSet = flags.RequiredInstructionSet