Ramdisk modules install to correct location

Install to recovery/root/first_stage_ramdisk if BOARD_USES_RECOVERY_AS_BOOT,
otherwise ramdisk. In addition, append /system if not InstallInRoot().

Test: pass
Bug: 147347110
Change-Id: Ie5895ac61a3d5d85f5d958a27c7980d6c79d997e
diff --git a/android/variable.go b/android/variable.go
index 2bf84dd..3228829 100644
--- a/android/variable.go
+++ b/android/variable.go
@@ -316,6 +316,8 @@
 	EnforceProductPartitionInterface *bool `json:",omitempty"`
 
 	InstallExtraFlattenedApexes *bool `json:",omitempty"`
+
+	BoardUsesRecoveryAsBoot *bool `json:",omitempty"`
 }
 
 func boolPtr(v bool) *bool {