Fix `tree-sitter-mozcpp` test failures introduced by #1141

[alexle0nte]

Following the grammar updates made by #1141, some tests are failing due to parsing errors in tree-sitter-cpp.
Below is a list of the failing tests and their corresponding upstream issues, meant to track the errors and fix the tests as the issues are resolved:

• test_fn_id_strings: #307
• DeepSpeech/native_client/deepspeech.cc: #308
• DeepSpeech/native_client/getopt_win.h: #308
• DeepSpeech/native_client/kenlm/util/mmap.cc: #308
• DeepSpeech/native_client/deepspeech.h: #309 and #310
• DeepSpeech/native_client/kenlm/util/double-conversion/fast-dtoa.cc: #311
• DeepSpeech/native_client/kenlm/lm/left_test.cc: #312
• DeepSpeech/native_client/ctcdecode/third_party/openfst-1.6.7/src/test/fst_test.h: #252
• DeepSpeech/native_client/ctcdecode/third_party/openfst-1.6.9-win/src/include/fst/test/fst_test.h: #252