ndk: Replace 'asm' with '__asm__' in <asm/byteorder.h>

See https://review.source.android.com/#change,20076 for details.
Essentially this is to allow compilation with -std=c99

Change-Id: I4c830c38b2615352765ee40773c5aa701e5d2b68

ndk/platforms/android-3/arch-arm/include/asm/byteorder.h

@@ -22,7 +22,7 @@ static inline __attribute_const__ __u32 ___arch__swab32(__u32 x)
 #ifndef __thumb__
  if (!__builtin_constant_p(x)) {
 
- asm ("eor\t%0, %1, %1, ror #16" : "=r" (t) : "r" (x));
+ __asm__ ("eor\t%0, %1, %1, ror #16" : "=r" (t) : "r" (x));
  } else
 #endif
  t = x ^ ((x << 16) | (x >> 16));