Remove OutputFile and Disassembler from libbcc.

For OutputFile, the code can be a lot simpler by just relying on what
llvm provides.

Disassembler was also not used.

Bug: 34265954
Test: Compiled.  Ran imageprocessing_jb and a compat lab test.
Test: Ran CTS.
Change-Id: I360a55541b6bbb9c104415e44920728c8d451446