Make lit tests work with filter argument

[stevenfontanella]

Example:

$ python3 check.py lit --filter='*gc-atomics*'
ninja: no work to do.
-- Testing: 6 tests, 6 workers --
PASS: Binaryen lit tests :: passes/optimize-instructions-gc-atomics.wast (1 of 6)
PASS: Binaryen lit tests :: passes/precompute-gc-atomics.wast (2 of 6)
PASS: Binaryen lit tests :: passes/vacuum-gc-atomics.wast (3 of 6)
PASS: Binaryen lit tests :: validation/gc-atomics.wast (4 of 6)
PASS: Binaryen lit tests :: basic/gc-atomics-null-refs.wast (5 of 6)
PASS: Binaryen lit tests :: basic/gc-atomics.wast (6 of 6)

Testing Time: 0.15s
  Passed: 6

[ success! ]

python3 check.py lit
ninja: no work to do.
-- Testing: 797 tests, 128 workers --
PASS: Binaryen lit tests :: binary/component-error.test (1 of 797)
PASS: Binaryen lit tests :: binary/bad-datacount.test (2 of 797)
...