Enable multiple custom toolchains

Change-Id: Ifcde6cbfe2782a7456f2b55386748227f593122a

Allow the use of multiple Linaro toolchains

Enable building with a8 optimized version of Linaro
Thanks to christopher!

If not using custom toolchain use default toolchain folder

Change-Id: I7a35c2a318d17fe3013b056c08b9cb1347b7b329
Prepare Mackay ROM script with info

Change-Id: If0d39ab673397462dc43d6bec48f6142d802fe2b
Revert "Include drawables for all densities - b/11270325"

This saves space on devices with low internal storage

This reverts commit 26c110c74456563e02eb2d117bec725575c40989.

Change-Id: Ic68644d3136bfc7792b349aecfd0c4cc42dcb03d
build: Add SKIP_SET_METADATA flag

On some of the older devices the recovery doesn't support
metadata when setting permissions. This allows to use
set_perm vs set_metadata.
Enable this behavior by setting SKIP_SET_METADATA := true

Change-Id: Ib6cf97b5ca28cee8a87975231f3a61b156e77d29