lexer: temporarily revert #\ patch; keep CR in comment bug fix

This commit temporarily reverts the commit that allows #\ "tcl-style"
comments everywhere and documents them, for the 1.7.1 patch release
cca1f7d18f.

\r is removed from the list of characters not allowed in a comment to
preserve that bugfix.

tests/shtest

@@ -594,24 +594,6 @@ if ! x=$($JQ -n "1 # foo$cr + 2") || [ "$x" != 1 ]; then
   exit 1
 fi
 
-if ! x=$($JQ -cn '[
-  1,
-  # foo \
-  2,
-  # bar \\
-  3,
-  4, # baz \\\
-  5, \
-  6,
-  7
-  # comment \
-    comment \
-    comment
-]') || [ "$x" != '[1,3,4,7]' ]; then
-  echo 'multiline comment was not handled correctly'
-  exit 1
-fi
-
 # Allow passing the inline jq script before -- #2919
 if ! r=$($JQ --args -rn -- '$ARGS.positional[0]' bar) || [ "$r" != bar ]; then
     echo "passing the inline script after -- didn't work"