[tools] Commit memory debug (et al) tooling

These are some changes I made to debug tooling while tracking down the
bugfix in the previous commit.

Each `scripts/debug_*_alloc.gdb` script has gdb output a `*_allocs.txt`
file, which in turn can be parsed by the `scripts/parse_*_allocs.py`
script to find errors.

.gitignore

@@ -13,3 +13,6 @@ sysroot
 __pycache__
 /venv
 compile_commands.json
+buddy_allocs.txt
+frame_allocs.txt
+heap_allocs.txt