Enable profiling JIT-ted code using OProfile
Support LLVM 3.0
Support LLVM 3.2
Support no LLVM
Create DICompileUnit to fix assertion error

There was a following assertion error:
  Assertion failed: (TheCU && "Unable to create DW_TAG_file_type without CompileUnit"), function createFile, file DIBuilder.cpp, line 129.

This occurs when using LLVM build with assertion enabled.
Invert LLVM API condition to follow coding style
Define user-defined DW_LANG_Ruby constant
Merge pull request #2192 from ryoqun/llvm-oprofile-jit

Enable profiling JIT-ted code using OProfile