Add a DEX2OAT_BOOTCLASSPATH variable.

Bug: 119800099
Test: m
Change-Id: If4b49b1bed33564b9237f8ae2ac35ef0d631703c
diff --git a/java/dexpreopt_config.go b/java/dexpreopt_config.go
index 31a3e26..280b601 100644
--- a/java/dexpreopt_config.go
+++ b/java/dexpreopt_config.go
@@ -196,6 +196,7 @@
 
 func dexpreoptConfigMakevars(ctx android.MakeVarsContext) {
 	ctx.Strict("PRODUCT_BOOTCLASSPATH", strings.Join(defaultBootclasspath(ctx), ":"))
+	ctx.Strict("PRODUCT_DEX2OAT_BOOTCLASSPATH", strings.Join(defaultBootImageConfig(ctx).dexLocations, ":"))
 	ctx.Strict("PRODUCT_SYSTEM_SERVER_CLASSPATH", strings.Join(systemServerClasspath(ctx), ":"))
 
 	ctx.Strict("DEXPREOPT_BOOT_JARS_MODULES", strings.Join(defaultBootImageConfig(ctx).modules, ":"))