sort and group includes

* includes are sorted alphabetically

* their grouping and layout is the following:
  - nsxiv.h will be the first include
  - followed by any internal headers (e.g "commands.h" "config.h")
  - followed by system headers (<stdlib.h> etc)
  - followed by third party headers (X.h libwebp etc)

* also add `llvm-include-order` check to clang-tidy so that it can catch
  unsorted includes during CI.

.woodpecker/clang-tidy-checks

@@ -1,6 +1,7 @@
 # checks
 clang-analyzer-*,clang-diagnostic-*,bugprone-*,performance-*,modernize-*
 misc-*,readability-*,android-cloexec-*,cert-*
+llvm-include-order
 
 # silence
 -misc-unused-parameters

autoreload.c

@@ -23,8 +23,8 @@
 #include <errno.h>
 #include <stdlib.h>
 #include <string.h>
-#include <unistd.h>
 #include <sys/inotify.h>
+#include <unistd.h>
 
 static union {
 	char d[4096]; /* aligned buffer */

commands.c

@@ -19,14 +19,14 @@
 
 #include "nsxiv.h"
 
-#include <stdlib.h>
-#include <stdio.h>
-#include <string.h>
-#include <unistd.h>
-#include <sys/wait.h>
-
 #include "commands.h"
 
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/wait.h>
+#include <unistd.h>
+
 extern img_t img;
 extern tns_t tns;
 extern win_t win;

main.c

@@ -22,22 +22,23 @@
 #include "commands.h"
 #include "config.h"
 
-#include <stdlib.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <locale.h>
+#include <poll.h>
+#include <signal.h>
 #include <stdarg.h>
 #include <stdio.h>
+#include <stdlib.h>
 #include <string.h>
-#include <fcntl.h>
-#include <unistd.h>
-#include <errno.h>
-#include <locale.h>
-#include <signal.h>
-#include <poll.h>
 #include <sys/stat.h>
+#include <sys/time.h>
 #include <sys/wait.h>
 #include <time.h>
-#include <sys/time.h>
-#include <X11/keysym.h>
+#include <unistd.h>
+
 #include <X11/XF86keysym.h>
+#include <X11/keysym.h>
 
 #define MODMASK(mask) ((mask) & USED_MODMASK)
 #define BAR_SEP "  "

nsxiv.h

@@ -20,8 +20,9 @@
 #ifndef NSXIV_H
 #define NSXIV_H
 
-#include <stddef.h>
 #include <stdbool.h>
+#include <stddef.h>
+
 #include <Imlib2.h>
 #include <X11/Xlib.h>
 

options.c

@@ -20,8 +20,8 @@
 #include "nsxiv.h"
 #include "version.h"
 
-#include <stdlib.h>
 #include <stdio.h>
+#include <stdlib.h>
 #include <string.h>
 #include <unistd.h>
 

util.c

@@ -20,13 +20,13 @@
 #include "nsxiv.h"
 
 #include <assert.h>
-#include <stdlib.h>
+#include <errno.h>
 #include <stdarg.h>
 #include <stdio.h>
+#include <stdlib.h>
 #include <string.h>
 #include <sys/stat.h>
 #include <unistd.h>
-#include <errno.h>
 
 const char *progname;
 

window.c

@@ -22,13 +22,14 @@
 #include "config.h"
 #include "icon/data.h"
 
+#include <locale.h>
 #include <stdlib.h>
 #include <string.h>
-#include <locale.h>
 #include <unistd.h>
-#include <X11/cursorfont.h>
+
 #include <X11/Xatom.h>
 #include <X11/Xresource.h>
+#include <X11/cursorfont.h>
 
 #if HAVE_LIBFONTS
 #include "utf8.h"