Add a way to pass GDB commands

Passing --gdb-arg to run-test sends the arg to GDB, example:
test/run-test --host --gdb --gdb-arg "--command=command.txt" 001-HelloWorld
Would run the test with the GDB script at command.txt on the host, this is
useful for running tests in GDB in a loop.

Bug: 17387969

Change-Id: I5ad455159a6d92783eacb17eecbb0f1e670cb4a3
2 files changed