libbtrfs: remove unneeded includes from kerncompat.h

Signed-off-by: David Sterba <dsterba@suse.com>

libbtrfs/kerncompat.h

@@ -26,17 +26,9 @@
 
 #include <stdio.h>
 #include <stdlib.h>
-#include <errno.h>
-#include <string.h>
 #include <endian.h>
 #include <byteswap.h>
-#include <assert.h>
 #include <stddef.h>
-#include <linux/types.h>
-#include <linux/const.h>
-#include <stdint.h>
-#include <stdbool.h>
-#include <features.h>
 
 /*
  * Libc compatibility.

tests/library-test.c

@@ -42,6 +42,8 @@
 #include "btrfs/send-utils.h"
 #endif
 
+#include <string.h>
+
 /*
  * Reduced code snippet from snapper.git/snapper/Btrfs.cc
  */