Reorder and reorganize header files

Let the includes in the following order:

< system headers >
< libkmod >
< tool >
< local headers >
diff --git a/testsuite/path.c b/testsuite/path.c
index f87f5c5..c27fabe 100644
--- a/testsuite/path.c
+++ b/testsuite/path.c
@@ -17,18 +17,18 @@
  */
 
 #include <assert.h>
-#include <errno.h>
 #include <dirent.h>
-#include <fcntl.h>
 #include <dlfcn.h>
+#include <errno.h>
+#include <fcntl.h>
 #include <limits.h>
-#include <stdlib.h>
 #include <stdarg.h>
-#include <string.h>
 #include <stdio.h>
-#include <sys/types.h>
-#include <sys/stat.h>
+#include <stdlib.h>
+#include <string.h>
 #include <unistd.h>
+#include <sys/stat.h>
+#include <sys/types.h>
 
 #include "testsuite.h"