[3DS] Fix crashes when loading savestates

The nonportable LE macros in Blargg SPU can allow unaligned loads,
which cause ARM exceptions on 3DS.

The portable code avoids these problems, and generates good enough
assembly, so it should be used instead.

src/blargg_endian.h

@@ -5,7 +5,7 @@
 #define BLARGG_ENDIAN
 
 /* Uncomment to enable platform-specific (and possibly non-portable) optimizations */
-#ifndef EMSCRIPTEN
+#if !defined(EMSCRIPTEN) && !defined(_3DS)
 #define BLARGG_NONPORTABLE 1
 #endif