Improve man page formatting

More closely follow common style as described on
https://man7.org/linux/man-pages/man7/man-pages.7.html
and fix warnings raised by `mandoc -T lint` and `groff -rCHECKSTYLE=10`

Signed-off-by: Alan Coopersmith <alan.coopersmith@oracle.com>
Part-of: <https://gitlab.freedesktop.org/xorg/driver/xf86-video-v4l/-/merge_requests/7>

man/v4l.man

@@ -1,7 +1,6 @@
-.\" $XFree86: xc/programs/Xserver/hw/xfree86/drivers/v4l/v4l.man,v 1.2 2001/01/27 18:20:55 dawes Exp $ 
 .\" shorthand for double quote that works everywhere.
 .ds q \N'34'
-.TH V4L __drivermansuffix__ __vendorversion__
+.TH V4L 4 2009-01-09 __vendorversion__
 .SH NAME
 v4l \- video4linux driver
 .SH SYNOPSIS
@@ -12,11 +11,15 @@ v4l \- video4linux driver
 .B EndSection
 .fi
 .SH DESCRIPTION
-.B v4l 
-is an __xservername__ driver for video4linux cards.  It provides a Xvideo
-extension port for video overlay.  Just add the driver to the module
-list within the module section of your __xconfigfile__ file if you want
-to use it.  There are no config options.
+.B v4l
+is an
+.B Xorg
+driver for video4linux cards.
+It provides a Xvideo extension port for video overlay.
+Just add the driver to the module list within the module section of your
+.B xorg.conf
+file if you want to use it.
+There are no config options.
 .P
 Note that the extmod module is also required for the Xvideo
 support (and lots of other extensions too).
@@ -30,10 +33,14 @@ overlay.
 bt848/bt878-based TV cards are the most popular hardware these
 days.
 .SH CONFIGURATION DETAILS
-Please refer to __xconfigfile__(__filemansuffix__) for general configuration
-details.  This section only covers configuration details specific to this
-driver.
+Please refer to
+.BR xorg.conf (5)
+for general configuration details.
+This section only covers configuration details specific to this driver.
 .SH "SEE ALSO"
-__xservername__(__appmansuffix__), __xconfigfile__(__filemansuffix__), Xserver(__appmansuffix__), X(__miscmansuffix__)
+.BR Xorg (1),
+.BR Xserver (1),
+.BR xorg.conf (5),
+.BR X (7)
 .SH AUTHORS
 Authors include: Gerd Knorr <kraxel@bytesex.org>

src/v4l.c

@@ -10,6 +10,10 @@
 #include "config.h"
 #endif
 
+#ifndef _GNU_SOURCE
+#define _GNU_SOURCE
+#endif
+
 #include <sys/types.h>
 #include <sys/stat.h>
 #include <ctype.h>
@@ -910,12 +914,9 @@ AddV4LEnc(XF86VideoEncodingPtr enc, int entry,
 {
     char *name;
 
-#if ABI_VIDEODRV_VERSION >= SET_ABI_VERSION(10, 0)
-    if (Xasprintf(&name, "%s-%s", norm, fixname(input)) < 0)
+    if (asprintf(&name, "%s-%s", norm, fixname(input)) < 0)
         name = NULL;
-#else
-    name = Xprintf("%s-%s", norm, fixname(input));
-#endif
+
     if (name == NULL)
         return -1;