Fix VNDK-Ext ABI check regression

VNDK-Ext are modules with `vndk.enabled: true` but not having
`vendor_available: true`.  In addition, VNDK-Ext should be checked by
source ABI checker.  This change fixes the regression introduced in

Bug: 110142940
Test: Create libminijail_ext, break some ABIs, and see an error.
Change-Id: I8b47ac12d2e132f641129c9549ed22c3971d6c89
diff --git a/cc/cc.go b/cc/cc.go
index 36b2f95..6438bcd 100644
--- a/cc/cc.go
+++ b/cc/cc.go
@@ -571,7 +571,7 @@
 		isVariantOnProductionDevice = sanitize.isVariantOnProductionDevice()
 	}
 	vendorAvailable := Bool(ctx.mod.VendorProperties.Vendor_available)
-	return !skipAbiChecks && isVariantOnProductionDevice && ctx.ctx.Device() && ((ctx.useVndk() && ctx.isVndk() && vendorAvailable) || inList(ctx.baseModuleName(), llndkLibraries))
+	return !skipAbiChecks && isVariantOnProductionDevice && ctx.ctx.Device() && ((ctx.useVndk() && ctx.isVndk() && (vendorAvailable || ctx.isVndkExt())) || inList(ctx.baseModuleName(), llndkLibraries))
 }
 
 func (ctx *moduleContextImpl) selectedStl() string {