Pass pctx and ctx to NewRuleBuilder

Enable the RuleBuilder and RuleBuilderCommand methods to access
the BuilderContext by passing it to NewRuleBuilder instead of
RuleBuilder.Build.

Test: genrule_test.go
Test: rule_builder_test.go
Test: m checkbuild
Change-Id: I63e6597e19167393876dc2259d6f521363b7dabc
diff --git a/java/dexpreopt.go b/java/dexpreopt.go
index a21fb76..67738d4 100644
--- a/java/dexpreopt.go
+++ b/java/dexpreopt.go
@@ -216,7 +216,7 @@
 		return dexJarFile
 	}
 
-	dexpreoptRule.Build(pctx, ctx, "dexpreopt", "dexpreopt")
+	dexpreoptRule.Build("dexpreopt", "dexpreopt")
 
 	d.builtInstalled = dexpreoptRule.Installs().String()