Update prebuilts for LLVM merge to r187914.

Change-Id: Ia02e3e03965f501117b05fb0691f69a89e7d1772
diff --git a/renderscript/clang-include/avx2intrin.h b/renderscript/clang-include/avx2intrin.h
index 63b1efc..1887fc8 100644
--- a/renderscript/clang-include/avx2intrin.h
+++ b/renderscript/clang-include/avx2intrin.h
@@ -25,6 +25,9 @@
 #error "Never use <avx2intrin.h> directly; include <immintrin.h> instead."
 #endif
 
+#ifndef __AVX2INTRIN_H
+#define __AVX2INTRIN_H
+
 /* SSE4 Multiple Packed Sums of Absolute Difference.  */
 #define _mm256_mpsadbw_epu8(X, Y, M) __builtin_ia32_mpsadbw256((X), (Y), (M))
 
@@ -1199,3 +1202,5 @@
   (__m256i)__builtin_ia32_gatherq_q256((__v4di)_mm256_setzero_si256(), \
              (const __v4di *)__m, (__v4di)__i, \
              (__v4di)_mm256_set1_epi64x(-1), (s)); })
+
+#endif /* __AVX2INTRIN_H */