double-conversion/utils.h: Add support of Synopsys ARC64 architecture (#170)

Signed-off-by: Veronika Kremneva <kremneva@synopsys.com>
diff --git a/double-conversion/utils.h b/double-conversion/utils.h
index fdf4b64..41078b6 100644
--- a/double-conversion/utils.h
+++ b/double-conversion/utils.h
@@ -141,7 +141,7 @@
     defined(_MIPS_ARCH_MIPS32R2) || defined(__ARMEB__) ||\
     defined(__AARCH64EL__) || defined(__aarch64__) || defined(__AARCH64EB__) || \
     defined(__riscv) || defined(__e2k__) || \
-    defined(__or1k__) || defined(__arc__) || \
+    defined(__or1k__) || defined(__arc__) || defined(__ARC64__) || \
     defined(__microblaze__) || defined(__XTENSA__) || \
     defined(__EMSCRIPTEN__) || defined(__wasm32__)
 #define DOUBLE_CONVERSION_CORRECT_DOUBLE_OPERATIONS 1