Build: update qcom_utils.mk

Add build macro to determine Android Release

Adding platform sdk version 18 for JB MR2.

Change-Id: I79aa831ddd335bd14bd777506c210acc5d9960f1
Merge "Build: update qcom_utils.mk" into cm-10.2
Merge branch 'cm-10.2' of https://github.com/CyanogenMod/android_build into cm-10.2