Part of issue #2168428: STOP SHIP: Bump API version to 5

This bumps the API version.  We are still going to be an Eclair
development version until prebuilts are updated.

Change-Id: Ie76f3cda15b6c2c0b924db614e8024c04ce5a035
diff --git a/core/version_defaults.mk b/core/version_defaults.mk
index a28d636..fd41239 100644
--- a/core/version_defaults.mk
+++ b/core/version_defaults.mk
@@ -53,7 +53,7 @@
   # intermediate builds).  During development, this number remains at the
   # SDK version the branch is based on and PLATFORM_VERSION_CODENAME holds
   # the code-name of the new development work.
-  PLATFORM_SDK_VERSION := 4
+  PLATFORM_SDK_VERSION := 5
 endif
 
 ifeq "" "$(PLATFORM_VERSION_CODENAME)"