build: Prevent some auto-generated variables from being overridden

These variables are used by internal processes for build indexing
and identification, and those processes expect either specific patterns,
or uniqueness.
So prevent accidental overriding of these by device configurations:
BUILD_DISPLAY_ID, BUILD_NUMBER, PLATFORM_VERSION, PLATFORM_SDK_VERSION,
PLATFORM_VERSION_CODENAME, BUILD_VERSION_TAGS

Change-Id: I06252f2687a5e5fd97ee21a98f26c739fd0ef6e4
Add f2fs to list of partition types in common.py

Change-Id: I9a54489c38009ca2970132b530164663b15c1337
build: Add script to generate extra images

Change-Id: I53081c7a2b4f18bc8c8a27b04d311a6b078b2022
Build: update qcom_utils.mk

Add build macro to determine Android Release

Adding platform sdk version 18 for JB MR2.

Change-Id: I79aa831ddd335bd14bd777506c210acc5d9960f1
build: Use common name for QCOM 7K boards.

This is needed to build QCOM HAL without external modifications. The
device would now have to specify msm7x27 or msm7x30 instead of
specifying the full name.

Patch Set 2: Add msm7x27a into the list.

Change-Id: I25018e397b5aad27fab5244731a574ae86752e17
qcom_utils: Add qsd8k to qcom platforms

PS2: fix typo

Change-Id: Id85569d1dd7be2f4c0620827da6d89e63b658aa9