tests: more automated quote adjustment

Relax initial regexp to match more instances, but add a
filter to avoid some invalid conversions.  Run this:

git grep -l "\`[^']*'" tests | xargs perl -pi -e '$q=q"'\''";' \
  -e '$q="$q\\$q$q"; /(= ?\`|\`expr|\`echo|\Q$q\E)/ and next;' \
  -e ' s/\`([^'\''"]*?'\'')/'\''$1/g'
The last disjunct in the above (...) filter is to exempt
any line that contains this string: '\''
With quoting like that, converting a ` to ' is likely to cause trouble,
so we'll handle those manually.  Here are three examples where
the exemption is required:

  *': `link-to-dir/'\'': hard link not allowed for directory'*) ;;
  printf 'creating file `%s'\''\n' $f
  'mv: inter-device move failed: `%s'\'' to `%s'\'';'\

1 files changed, 1 insertions, 1 deletions

diff --git a/tests/misc/xstrtol b/tests/misc/xstrtol
index bdc7bff28..fa0056fcd 100755
--- a/tests/misc/xstrtol
+++ b/tests/misc/xstrtol
@@ -39,7 +39,7 @@ my @Tests =
     {ERR=>"$prog: invalid --pages argument 'x'\n"}],
 
    ['inv-pg-range', "--pages=9x", {EXIT => 1},
-    {ERR=>"$prog: invalid page range `9x'\n"}],
+    {ERR=>"$prog: invalid page range '9x'\n"}],
   );
 
 my $save_temps = $ENV{DEBUG};