Update the test scenario for find_global_variables() to now start the inferior process

before issuing API calls to find the global variable and to get its value.

rdar://problem/9700873 has been updated to reflect the latest status.  The dwarf case
now does not seg fault if the inferior is not started; instead, for dwarf case, the
value retrieved from the global variable is None.

llvm-svn: 134909