Fix bp2build-progress generating an empty converted_modules list, and
duplicate module names.

We were using the value receiver on AddConvertedModule before, which
didn't actually mutate the internal slice state.

Test: Run bp2build-progress.py
Change-Id: Ic60f8f6214a91dc129abf62c57dd0b85efffb283
diff --git a/bp2build/metrics.go b/bp2build/metrics.go
index 55b928b..9e7b3b6 100644
--- a/bp2build/metrics.go
+++ b/bp2build/metrics.go
@@ -24,7 +24,7 @@
 }
 
 // Print the codegen metrics to stdout.
-func (metrics CodegenMetrics) Print() {
+func (metrics *CodegenMetrics) Print() {
 	generatedTargetCount := 0
 	for _, ruleClass := range android.SortedStringKeys(metrics.RuleClassCount) {
 		count := metrics.RuleClassCount[ruleClass]
@@ -40,7 +40,7 @@
 		strings.Join(metrics.moduleWithUnconvertedDepsMsgs, "\n\t"))
 }
 
-func (metrics CodegenMetrics) AddConvertedModule(moduleName string) {
+func (metrics *CodegenMetrics) AddConvertedModule(moduleName string) {
 	// Undo prebuilt_ module name prefix modifications
 	moduleName = android.RemoveOptionalPrebuiltPrefix(moduleName)
 	metrics.convertedModules = append(metrics.convertedModules, moduleName)