Add vendor-ramdisk image to Soong.

Add vendor_ramdisk_available and vendor_ramdisk attribute to
various rules. When a vendor_ramdisk variant of a module is
generated, it is installed to $OUT/vendor-ramdisk.

It is similar to a ramdisk image.
Test: m nothing -j

Change-Id: Ib2d16459f3094dbe21c3bdb7c016cb4b2bf62765
diff --git a/android/paths.go b/android/paths.go
index 3825d45..8fd2e88 100644
--- a/android/paths.go
+++ b/android/paths.go
@@ -58,6 +58,7 @@
 	InstallInTestcases() bool
 	InstallInSanitizerDir() bool
 	InstallInRamdisk() bool
+	InstallInVendorRamdisk() bool
 	InstallInRecovery() bool
 	InstallInRoot() bool
 	InstallBypassMake() bool
@@ -1376,6 +1377,9 @@
 			if !ctx.InstallInRoot() {
 				partition += "/system"
 			}
+		} else if ctx.InstallInVendorRamdisk() {
+			// TODO(elsk): Should be conditional on move_recovery_res_to_vendor_boot
+			partition = "vendor-ramdisk"
 		} else if ctx.InstallInRecovery() {
 			if ctx.InstallInRoot() {
 				partition = "recovery/root"