Use two-column format for PRODUCT_BOOT_JARS components.

The first component is the apex name, or a special name "platform"
if the boot jar is a platform jar rather than a part of some apex.
This is a prerequisite change for moving core-icu4j to a separate
com.android.i18n apex.

Old one-column format is still supported, but all unqualified
components of PRODUCT_BOOT_JARS get "platform:" prepended to them
after reading the product makefiles.

Test: aosp_walleye-userdebug boots
Bug: 138994281
Change-Id: Ic229159fdcdaf6182210a53b63850a389dd786fc
diff --git a/java/dexpreopt_bootjars_test.go b/java/dexpreopt_bootjars_test.go
index 127c201..0946bf0 100644
--- a/java/dexpreopt_bootjars_test.go
+++ b/java/dexpreopt_bootjars_test.go
@@ -48,7 +48,7 @@
 
 	pathCtx := android.PathContextForTesting(config)
 	dexpreoptConfig := dexpreopt.GlobalConfigForTests(pathCtx)
-	dexpreoptConfig.BootJars = []string{"foo", "bar", "baz"}
+	dexpreoptConfig.BootJars = []string{"platform:foo", "platform:bar", "platform:baz"}
 	dexpreopt.SetTestGlobalConfig(config, dexpreoptConfig)
 
 	ctx := testContext()