Add debug ramdisk variant

A module will be installed to debug_ramdisk (or
debug_ramdisk/first_stage_ramdisk if recovery as boot is true) if
debug_ramdisk is set to true.

Bug: 184004542
Test: soong test
Change-Id: Ic5a4d27407e506fffa462de2149e0785f11b2ac7
diff --git a/cc/genrule.go b/cc/genrule.go
index ca4fda7..82d7205 100644
--- a/cc/genrule.go
+++ b/cc/genrule.go
@@ -75,6 +75,10 @@
 	return Bool(g.Vendor_ramdisk_available)
 }
 
+func (g *GenruleExtraProperties) DebugRamdiskVariantNeeded(ctx android.BaseModuleContext) bool {
+	return false
+}
+
 func (g *GenruleExtraProperties) RecoveryVariantNeeded(ctx android.BaseModuleContext) bool {
 	// If the build is using a snapshot, the recovery variant under AOSP directories
 	// is not needed.