Make CreateArgv part of lli rather than part of ExecutionEngine.

Switch Interpreter and JIT's "run" methods to take a Function and a vector of
 GenericValues.
Move (almost all of) the stuff that constructs a canonical call to main()
 into lli (new methods "callAsMain", "makeStringVector").
Nuke getCurrentExecutablePath(), enableTracing(), getCurrentFunction(),
 isStopped(), and many dead decls from interpreter.
Add linux strdup() support to interpreter.
Make interpreter's atexit handler runner and JIT's runAtExitHandlers() look
 more alike, in preparation for refactoring.
atexit() is spelled "atexit", not "at_exit".

llvm-svn: 8366