fix armclang build fail for sha512.

`sha3` support is start from armclang6.10

Signed-off-by: Jerry Yu <jerry.h.yu@arm.com>
diff --git a/library/sha512.c b/library/sha512.c
index 5174b65..fc7de74 100644
--- a/library/sha512.c
+++ b/library/sha512.c
@@ -77,7 +77,13 @@
  */
 #    if !defined(__ARM_FEATURE_SHA512) || defined(MBEDTLS_ENABLE_ARM_SHA3_EXTENSIONS_COMPILER_FLAG)
        /* Test Clang first, as it defines __GNUC__ */
-#      if defined(__clang__)
+#      if defined(__ARMCOMPILER_VERSION)
+#        if __ARMCOMPILER_VERSION < 6090000
+#          error "A more recent ArmClang is required for MBEDTLS_SHA512_USE_A64_CRYPTO_*"
+#        endif
+#          pragma clang attribute push (__attribute__((target("sha3"))), apply_to=function)
+#          define MBEDTLS_POP_TARGET_PRAGMA
+#      elif defined(__clang__)
 #        if __clang_major__ < 7
 #          error "A more recent Clang is required for MBEDTLS_SHA512_USE_A64_CRYPTO_*"
 #        else