Add back version flag to prepare for release

config.mk

@@ -11,7 +11,7 @@ X11INC = /usr/X11R6/include
 X11LIB = /usr/X11R6/lib
 
 # flags
-CPPFLAGS = -I$(X11INC) -D_DEFAULT_SOURCE
+CPPFLAGS = -I$(X11INC) -D_DEFAULT_SOURCE -DVERSION=\"${VERSION}\"
 CFLAGS   = -std=c99 -pedantic -Wall -Wextra -Wno-unused-parameter -Os
 LDFLAGS  = -L$(X11LIB) -s
 # OpenBSD: add -lsndio

slstatus.1

@@ -22,6 +22,8 @@ By default,
 outputs to WM_NAME.
 .Sh OPTIONS
 .Bl -tag -width Ds
+.It Fl v
+Print version information to stderr, then exit.
 .It Fl s
 Write to stdout instead of WM_NAME.
 .It Fl 1

slstatus.c

@@ -41,7 +41,7 @@ difftimespec(struct timespec *res, struct timespec *a, struct timespec *b)
 static void
 usage(void)
 {
-	die("usage: %s [-s] [-1]", argv0);
+	die("usage: %s [-v] [-s] [-1]", argv0);
 }
 
 int
@@ -56,6 +56,8 @@ main(int argc, char *argv[])
 
 	sflag = 0;
 	ARGBEGIN {
+	case 'v':
+		die("slstatus-"VERSION);
 	case '1':
 		done = 1;
 		/* FALLTHROUGH */