wc: Fix usage and manual SYNOPSIS + nits

The -c and -m flags are mututally exclusive. Also minor manual fixes:

+ Angle quotes do not work in prose, use double quote matching extant
+ Align manual page options list
+ Tag SPDX license identifier for manual

PR:		292408
MFC after:	3 days

usr.bin/wc/wc.1

@@ -1,3 +1,6 @@
+.\"
+.\" SPDX-License-Identifier: BSD-3-Clause
+.\"
 .\" Copyright (c) 1991, 1993
 .\"	The Regents of the University of California.  All rights reserved.
 .\"
@@ -37,7 +40,8 @@
 .Sh SYNOPSIS
 .Nm
 .Op Fl -libxo
-.Op Fl Lclmw
+.Op Fl c | Fl m
+.Op Fl Llw
 .Op Ar
 .Sh DESCRIPTION
 The
@@ -47,10 +51,10 @@ input
 .Ar file ,
 or standard input (if no file is specified) to the standard output.
 A line is defined as a string of characters delimited by a
-.Aq newline
+.Dq newline
 character.
 Characters beyond the final
-.Aq newline
+.Dq newline
 character will not be included
 in the line count.
 .Pp
@@ -64,7 +68,7 @@ for all the files is displayed on a separate line after the output for
 the last file.
 .Pp
 The following options are available:
-.Bl -tag -width indent
+.Bl -tag -width "--libxo"
 .It Fl -libxo
 Generate output via
 .Xr libxo 3

usr.bin/wc/wc.c

@@ -353,6 +353,6 @@ word:	gotsp = true;
 static void
 usage(void)
 {
-	xo_error("usage: wc [-Lclmw] [file ...]\n");
+	xo_error("usage: wc [-c | -m] [-Llw] [file ...]\n");
 	exit(EXIT_FAILURE);
 }