gdb/testsuite: give binaries distinct names in Ada tests

Some Ada tests repeat their test sequence with different gnat-encodings,
typically "all" and "minimal".  However, they give the same name to both
binaries, meaning the second run overwrites the binary of the first run.
This makes it difficult and confusing when trying to reproduce problems
manually with the test artifacts.  Change those tests to use unique
names for each pass.

Change-Id: Iaa3c9f041241249a7d67392e785c31aa189dcc88