Added two test cases to TestSettings.py which exercise the lldb's:

(lldb) settings set process.run-args A B C
(lldb) settings set process.env-vars ["MY_ENV_VAR"]=YES

commands.  The main.cpp checks whether A, B, C is passed to main and whether
the $MY_ENV_VAR env variable is defined and outputs the findings to a file.

llvm-svn: 114031