MIPS: Add __SANE_USERSPACE_TYPES__ to asm/types.h for LL64

Allow 64-bit userspace programs to use ll64 types. The define name
comes from commit 2c9c6ce0 (powerpc:
Add __SANE_USERSPACE_TYPES__ to asm/types.h for LL64).

The patch allows to compile perf on MIPS64 and eliminates the following
warnings:

tests/attr.c:74:4: error: format '%llu' expects argument of type 'long
long unsigned int', but argument 6 has type '__u64' [-Werror=format=]
Signed-off-by: NAaro Koskinen <aaro.koskinen@nsn.com>
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/6890/Signed-off-by: NRalf Baechle <ralf@linux-mips.org>

arch/mips/include/uapi/asm/types.h

@@ -14,9 +14,12 @@
 /*
  * We don't use int-l64.h for the kernel anymore but still use it for
  * userspace to avoid code changes.
+ *
+ * However, some user programs (e.g. perf) may not want this. They can
+ * flag __SANE_USERSPACE_TYPES__ to get int-ll64.h here.
  */
 #ifndef __KERNEL__
-# if _MIPS_SZLONG == 64
+# if _MIPS_SZLONG == 64 && !defined(__SANE_USERSPACE_TYPES__)
 #  include <asm-generic/int-l64.h>
 # else
 #  include <asm-generic/int-ll64.h>