delete leading junk before attempting JSON decode

- This is so when grepping multiple files or recursively grepping
  directories, you don't have to add the -h flag to grep to prevent
  it from prepending filenames to the matching lines.

bin/log-defer-viz

@@ -176,6 +176,7 @@ while (my $file = shift) {
     my $entry;
 
     try {
+      $_ =~ s/^[^{]+//; ## grep -r prepends filename (this is so you don't to remember the the -h flag)
       $entry = decode_json($_);
     } catch {
       if ($opt->{verbose}) {