Before:
  runtime ale_linters/awk/gawk.vim

After:
  call ale#linter#Reset()

Execute(gawk syntax errors should be parsed correctly):
  AssertEqual
  \ [
  \   {
  \     'lnum': 1,
  \     'col': 0,
  \     'text': "invalid char ''' in expression",
  \     'code': 0,
  \     'type': 'E',
  \   },
  \   {
  \     'lnum': 5,
  \     'col': 0,
  \     'text': 'unterminated string',
  \     'code': 0,
  \     'type': 'E',
  \   },
  \   {
  \     'lnum': 10,
  \     'col': 0,
  \     'text': "escape sequence `\u' treated as plain `u'",
  \     'code': 0,
  \     'type': 'W',
  \   },
  \ ],
  \ ale#handlers#gawk#HandleGawkFormat(347, [
  \   "gawk: something.awk:1: BEGIN { system('touch aaaaaaaaa') }",
  \   "gawk: something.awk:1:                ^ invalid char ''' in expression",
  \   'gawk: something.awk:5: { x = "aaaaaaaaaaa',
  \   'gawk: something.awk:5:       ^ unterminated string',
  \   "gawk: something.awk:10: warning: escape sequence `\u' treated as plain `u'",
  \ ])
