BugDriver.h:

* Added method to query if BugDriver is executing the JIT currently.
  This provides the ability in adding code that is conditionally executed in
  codegen debugging phase.

CodeGeneratorBug.cpp:
* Delete test functions from the Safe module
* Code conditionally added when debugging the JIT:
  use the lazy resolver function added to Emitter.cpp to get function pointer
  by name. When compiled into an .so, this is the only way to get a pointer to
  an external function
* Added a symbol disambiguator which will keep symbols uniquely named across
  modules
* Delete generated files by default
* The function `main' *must* stay in the .bc file for the JIT, but that prevents
  debugging it alone. This patch makes the old `main' become `old_main' and adds
  a new function named `main' which just calls the original with the same
  parameters, thereby keeping functionality the same.

ExecutionDriver.cpp:
* Returned to getting unique filenames
* Simplified code choosing between using and not using shared library option

llvm-svn: 7364