Add more define-detection for ARM64.

Fixes #6.
diff --git a/src/utils.h b/src/utils.h
index 62de6d8..2609efa 100644
--- a/src/utils.h
+++ b/src/utils.h
@@ -62,7 +62,7 @@
     defined(__sparc__) || defined(__sparc) || defined(__s390__) || \
     defined(__SH4__) || defined(__alpha__) || \
     defined(_MIPS_ARCH_MIPS32R2) || \
-    defined(__AARCH64EL__)
+    defined(__AARCH64EL__) || defined(__aarch64__)
 #define DOUBLE_CONVERSION_CORRECT_DOUBLE_OPERATIONS 1
 #elif defined(__mc68000__)
 #undef DOUBLE_CONVERSION_CORRECT_DOUBLE_OPERATIONS