posix_types: Make it possible to override __kernel_fsid_t

__kernel_fsid_t has members of type "long" on at least one
architecture (MIPS32), so make it possible to override the definition.

Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Link: http://lkml.kernel.org/r/1328677745-20121-3-git-send-email-hpa@zytor.com
Cc: Arnd Bergmann <arnd@arndb.de>

include/asm-generic/posix_types.h

@@ -73,6 +73,12 @@ typedef long		__kernel_ptrdiff_t;
 #endif
 #endif
 
+#ifndef __kernel_fsid_t
+typedef struct {
+	int	val[2];
+} __kernel_fsid_t;
+#endif
+
 /*
  * anything below here should be completely generic
  */
@@ -86,10 +92,6 @@ typedef char *		__kernel_caddr_t;
 typedef unsigned short	__kernel_uid16_t;
 typedef unsigned short	__kernel_gid16_t;
 
-typedef struct {
-	int	val[2];
-} __kernel_fsid_t;
-
 #ifdef __KERNEL__
 
 #undef __FD_SET