maint: update quoting of "Try `prog --help'" to "Try 'prog --help'"

Automatically adjust both the source (now in only one place)
and all tests that expect the resulting output via this:

git grep -l 'Try.*--help' src/system.h tests \
  | xargs perl -pi -e 's/Try \\?`(\S+ --help)/Try '\''$1/'

1 files changed, 1 insertions, 1 deletions

diff --git a/tests/misc/tsort b/tests/misc/tsort
index 0bc2a2ca2..88fcec50a 100755
--- a/tests/misc/tsort
+++ b/tests/misc/tsort
@@ -55,7 +55,7 @@ my @Tests =
    ['only-one', {IN => {f => ""}}, {IN => {g => ""}},
     {EXIT => 1},
     {ERR => "tsort: extra operand `g'\n"
-     . "Try `tsort --help' for more information.\n"}],
+     . "Try 'tsort --help' for more information.\n"}],
   );
 
 my $save_temps = $ENV{DEBUG};