Simplify acquisition of debug informtion for instruction info with newer LLVM versions

With newer LLVM versions (starting with LLVM 2.7) debug information are directly associated
as meta data with each instruction.
Therefore, debug information can be acquired directly from each instruction.
Allow to specify KLEE-internal functions

KLEE provides runtime library functions to do detection of bugs (e.g. overflow).
This runtime functions are not the location of the bugs but it is
the next non-runtime library function from the stack.
Use the caller inside that function to indicate where the bug is.
Replicate debug information from checked instructions to checker call.
Optimize inlineChecks function

* Just iterate over the instructions which use the function to be inlined
* Handle each callsite (e.g. CallInst and InvokeInst)