[mips] Switch asm to __asm__ for non-GNU compiles.

[srhines]

Summary

Using asm works fine for gnu11, but fails if the compiler uses C11.
Switch to the more consistent asm, since that is what the rest of
the source is using.

lib/builtins/clear_cache.c

#if defined(__mips__)
   #include <sys/cachectl.h>
   #include <sys/syscall.h>
   #include <unistd.h>
   #if defined(__ANDROID__) && defined(__LP64__)
     /*
      * clear_mips_cache - Invalidates instruction cache for Mips.
      */
     static void clear_mips_cache(const void* Addr, size_t Size) {
-      asm volatile (
+      __asm__ volatile (
         ".set push\n"
         ".set noreorder\n"
         ".set noat\n"
         "beq %[Size], $zero, 20f\n"          /* If size == 0, branch around. */
         "nop\n"
         "daddu %[Size], %[Addr], %[Size]\n"  /* Calculate end address + 1 */
         "rdhwr $v0, $1\n"                    /* Get step size for SYNCI.
                                                 $1 is $HW_SYNCI_Step */