Add GCC version to testsuite run output and systemtap.sum file.

Add GCC version to testsuite run output and systemtap.sum file.

Prints the gcc being used and full version. Also adds short version
number to systemtap.sum file (plus full version string). Will make
comparing failures based on compiler version being used easier.

* testsuite/lib/systemtap.exp (print_systemtap_version): Also print
  location and full version of gcc being used.
  (get_system_info): Get gcc version number and long version string.
* testsuite/lib/stap_run.exp (print_system_info): Output GCC version.