Tweaked/fixed a number of small runner things after a bit of use

- Added support for negative numbers in the leb16 encoding with an
  optional 'w' prefix.

- Changed prettyasserts.py rule to .a.c => .c, allowing other .a.c files
  in the future.

- Updated .gitignore with missing generated files (tags, .csv).

- Removed suite-namespacing of test symbols, these are no longer needed.

- Changed test define overrides to have higher priority than explicit
  defines encoded in test ids. So:

    ./runners/bench_runner bench_dir_open:0f1g12gg2b8c8dgg4e0 -DREAD_SIZE=16

  Behaves as expected.

  Otherwise it's not easy to experiment with known failing test cases.

- Fixed issue where the -b flag ignored explicit test/bench ids.

.gitignore

@@ -4,19 +4,31 @@
 *.a
 *.ci
 *.csv
-*.t.c
-*.b.c
-*.a.c
+*.t.*
+*.b.*
 *.gcno
 *.gcda
 *.perf
+lfs
+liblfs.a
 
 # Testing things
-blocks/
-lfs
-test.c
-tests/*.toml.*
-scripts/__pycache__
-.gdb_history
 runners/test_runner
 runners/bench_runner
+lfs.code.csv
+lfs.data.csv
+lfs.stack.csv
+lfs.structs.csv
+lfs.cov.csv
+lfs.perf.csv
+lfs.perfbd.csv
+lfs.test.csv
+lfs.bench.csv
+
+# Misc
+tags
+.gdb_history
+scripts/__pycache__
+
+# Historical, probably should remove at some point
+tests/*.toml.*