Backport from upstream.

https://code.google.com/p/double-conversion/source/detail?r=4e24bb31bcc76d6d218f3056b4c24a109d367561

---
 mfbt/double-conversion/utils.h |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/mfbt/double-conversion/utils.h
+++ b/mfbt/double-conversion/utils.h
@@ -58,11 +58,11 @@
     defined(__mips__) || \
     defined(__powerpc__) || defined(__ppc__) || defined(__ppc64__) || \
     defined(__sparc__) || defined(__sparc) || defined(__s390__) || \
     defined(__SH4__) || defined(__alpha__) || \
     defined(_MIPS_ARCH_MIPS32R2) || \
-    defined(_AARCH64EL_)
+    defined(__AARCH64EL__)
 #define DOUBLE_CONVERSION_CORRECT_DOUBLE_OPERATIONS 1
 #elif defined(_M_IX86) || defined(__i386__) || defined(__i386)
 #if defined(_WIN32)
 // Windows uses a 64bit wide floating point stack.
 #define DOUBLE_CONVERSION_CORRECT_DOUBLE_OPERATIONS 1