add support for a new architecture loongarch. (#162)

Signed-off-by: houfangdong <xianhfd@gmail.com>
Signed-off-by: houfangdong <houfangdong@loongson.cn>

Co-authored-by: yxh131466 <yxh131466520@126.com>
diff --git a/Changelog b/Changelog
index a3add38..63f2a8a 100644
--- a/Changelog
+++ b/Changelog
@@ -1,3 +1,7 @@
+2021-05-19:
+  Loongarch is a RISC-style command system architecture.
+  Add support for loongarch architecture.
+
 2020-02-16:
   Add support for quiet and signaling NaNs to ieee header.
 
diff --git a/double-conversion/utils.h b/double-conversion/utils.h
index c72c333..c84c0fa 100644
--- a/double-conversion/utils.h
+++ b/double-conversion/utils.h
@@ -108,6 +108,7 @@
     defined(__ARMEL__) || defined(__avr32__) || defined(_M_ARM) || defined(_M_ARM64) || \
     defined(__hppa__) || defined(__ia64__) || \
     defined(__mips__) || \
+    defined(__loongarch__) || \
     defined(__nios2__) || defined(__ghs) || \
     defined(__powerpc__) || defined(__ppc__) || defined(__ppc64__) || \
     defined(_POWER) || defined(_ARCH_PPC) || defined(_ARCH_PPC64) || \