Add native_coverage to product variables

Allow native_coverage to adjust sources in product_variables.

Fixes: 148088129
Test: m checkbuild
Change-Id: I9c9d491cda92d69726a0d598408de2060241365b
diff --git a/android/config.go b/android/config.go
index 5c4f0a8..cd24b24 100644
--- a/android/config.go
+++ b/android/config.go
@@ -1024,7 +1024,7 @@
 }
 
 func (c *deviceConfig) NativeCoverageEnabled() bool {
-	return Bool(c.config.productVariables.NativeCoverage)
+	return Bool(c.config.productVariables.Native_coverage)
 }
 
 func (c *deviceConfig) ClangCoverageEnabled() bool {