mips: intreadwrite: Only execute that code for mips r1 or r2

MIPS R6 supports unaligned memory access and does not have
the load/store-left/right family of instructions.

Signed-off-by: Vicente Olivert Riera <Vincent.Riera at imgtec.com>
Signed-off-by: Luca Barbato <lu_zero at gentoo.org>
Signed-off-by: Luca Barbato <lu_zero@gentoo.org>

libavutil/mips/intreadwrite.h

@@ -24,7 +24,13 @@
 #include <stdint.h>
 #include "config.h"
 
-#if ARCH_MIPS64 && HAVE_INLINE_ASM
+/*
+ * GCC actually handles unaligned accesses correctly in all cases
+ * except, absurdly, 32-bit loads on mips64.
+ *
+ * https://git.libav.org/?p=libav.git;a=commit;h=b82b49a5b774b6ad9119e981c72b8f594fee2ae0
+ */
+#if HAVE_MIPS64R2_INLINE || HAVE_MIPS64R1_INLINE
 
 #define AV_RN32 AV_RN32
 static av_always_inline uint32_t AV_RN32(const void *p)
@@ -41,6 +47,6 @@ static av_always_inline uint32_t AV_RN32(const void *p)
     return v;
 }
 
-#endif /* ARCH_MIPS64 && HAVE_INLINE_ASM */
+#endif /* HAVE_MIPS64R2_INLINE || HAVE_MIPS64R1_INLINE */
 
 #endif /* AVUTIL_MIPS_INTREADWRITE_H */