Change the location we include linux/xattr.h

This header stuff seems a bit fragile, but Serge reports including
it in sys/capability.h was causing a lot of trouble building dependent
app packages.

From the perspective of libcap, this API is only needed internally in
cap_file.c so we put an include there.

Signed-off-by: Andrew G Morgan <morgan@kernel.org>
diff --git a/libcap/cap_file.c b/libcap/cap_file.c
index d3dc1d0..553c2d2 100644
--- a/libcap/cap_file.c
+++ b/libcap/cap_file.c
@@ -10,6 +10,8 @@
 #include <sys/stat.h>
 #include <unistd.h>
 
+#include <linux/xattr.h>
+
 #define XATTR_SECURITY_PREFIX "security."
 
 #include "libcap.h"
diff --git a/libcap/include/sys/capability.h b/libcap/include/sys/capability.h
index 64ac50e..dddc75b 100644
--- a/libcap/include/sys/capability.h
+++ b/libcap/include/sys/capability.h
@@ -27,7 +27,6 @@
 #define __user
 #endif
 #include <linux/capability.h>
-#include <linux/xattr.h>
 
 /*
  * POSIX capability types