[scripts] Use correct compile-time regex syntax in split_scp.pl (#3287)

Regular expressions should be written with // to allow the language to do compile-time checks for the regexp pattern. This is from `perldoc perlop`: If the right argument is an expression rather than a search pattern, substitution, or transliteration, it is interpreted as a search pattern at run time. Note that this means that its contents will be interpolated twice, so '\\' =~ q'\\'; is not ok, as the regex engine will end up trying to compile the pattern "\", which it will consider a syntax error.

Author: xsawyerx

egs/wsj/s5/utils/split_scp.pl

@@ -55,7 +55,7 @@
  die "Invalid num-jobs and job-id: $num_jobs and $job_id";
  }
  }
- if ($ARGV[0] =~ "--utt2spk=(.+)") {
+ if ($ARGV[0] =~ /--utt2spk=(.+)/) {
  $utt2spk_file=$1;
  shift;
  }