Use product variables from the overridden apex

override_apex's bp2build converter had a bug where it was looking at
the product variables for the override_apex module itself instead of
for the base module it is overriding.

Fixes: 271424349
Test: go test
Change-Id: If1e2653d3751fa908faf0ab97dfa2e943ebe98ec
diff --git a/cc/bp2build.go b/cc/bp2build.go
index 1ea8bda..8644bf6 100644
--- a/cc/bp2build.go
+++ b/cc/bp2build.go
@@ -766,7 +766,7 @@
 		nativeCoverage = BoolPtr(false)
 	}
 
-	productVariableProps := android.ProductVariableProperties(ctx)
+	productVariableProps := android.ProductVariableProperties(ctx, ctx.Module())
 
 	(&compilerAttrs).convertProductVariables(ctx, productVariableProps)
 	(&linkerAttrs).convertProductVariables(ctx, productVariableProps)