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/android/arch.go b/android/arch.go
index 6826f3b..e40b6f5 100644
--- a/android/arch.go
+++ b/android/arch.go
@@ -618,7 +618,7 @@
 	}
 
 	// only the primary arch in the ramdisk / vendor_ramdisk / recovery partition
-	if os == Android && (module.InstallInRecovery() || module.InstallInRamdisk() || module.InstallInVendorRamdisk()) {
+	if os == Android && (module.InstallInRecovery() || module.InstallInRamdisk() || module.InstallInVendorRamdisk() || module.InstallInDebugRamdisk()) {
 		osTargets = []Target{osTargets[0]}
 	}