Screen bitcode for non-RS functions before linking with runtime lib

Bug: 19425238
Bug: 20894432

Perform the screening of non-RenderScript functions in the script before
linking against the runtime lib.  Previously, this used to be done after
linking with the runtime lib, LTO passes and just before code

This allows vendors to link against a different runtime library that may
not have all the functions as the CPU reference driver and add new
builtins specific to their driver.

Moreover, symbols introduced by LLVM optimizations no longer need any
special handling.

Change-Id: I5628aa15547a9d56ef7e6550fcb45e8ffa821ade
3 files changed