[CI20] Skip msync syscall

msync syscall is not supported, so skip it.

Change-Id: I9f44839225ef1343e3ceca96ce8ed3bcb8b42fe8
diff --git a/src/starboard/shared/posix/memory_flush.cc b/src/starboard/shared/posix/memory_flush.cc
index 46611d5..61dadd9 100644
--- a/src/starboard/shared/posix/memory_flush.cc
+++ b/src/starboard/shared/posix/memory_flush.cc
@@ -27,7 +27,7 @@
 
 void SbMemoryFlush(void* virtual_address, int64_t size_bytes) {
   char* memory = reinterpret_cast<char*>(virtual_address);
-#if !SB_IS(ARCH_ARM)
+#if !SB_IS(ARCH_ARM) && !SB_IS(ARCH_MIPS)
   int result = msync(memory, size_bytes, MS_SYNC);
   SB_DCHECK(result == 0) << "msync failed: 0x" << std::hex << result << " ("
                          << std::dec << result << "d)";