Re-order the ext/framework boot jars in bootclasspath.

Order of those doesn't matter, and the new order simplifies b/119800099.

Test: m and boots
Bug: 119800099
Change-Id: I9667a8d49ae751dfe713e37483548a58dfb25bd4
diff --git a/target/product/base_system.mk b/target/product/base_system.mk
index ec463f7..d30ca29 100644
--- a/target/product/base_system.mk
+++ b/target/product/base_system.mk
@@ -311,11 +311,11 @@
 $(error TARGET_CORE_JARS is empty; cannot initialize PRODUCT_BOOT_JARS variable)
 endif
 
-# The order matters
+# The order matters for runtime class lookup performance.
 PRODUCT_BOOT_JARS := \
     $(TARGET_CORE_JARS) \
-    ext \
     framework \
+    ext \
     telephony-common \
     voip-common \
     ims-common