[BOLT] Move disassemble optimizations to optimization passes

Summary:
The patch moves the shortenInstructions and nop remove to separate binary
passes. As a result when llvm-bolt optimizations stage will begin the
instructions of the binary functions will be absolutely the same as it
was in the binary. This is needed for the golang support by llvm-bolt.
Some of the tests must be changed, since bb alignment nops might create
unreachable BBs in original functions.

Vladislav Khmelevsky,
Advanced Software Technology Lab, Huawei

(cherry picked from FBD32896517)