Add support for running auto-tests under gdb

 - All auto tests are run under gdb in batch mode
 - Common file (.gdb_setup in LINKER_DIR) can be used to define breakpoints
 - Output isn't captured so only success or failure of a test
   script is reported
Activate teh elfStringTable Tests

Identifies a bug with the section string table
Fix bug string table bug

The string table section header is now correctly written