Merge latest changes from http://www.netlib.org/fp/dtoa.c into dtoa.cc

base/third_party/dmg_fp/const_hexdig.patch

Index: base/third_party/dmg_fp/const_hexdig.patch
diff --git a/base/third_party/dmg_fp/const_hexdig.patch b/base/third_party/dmg_fp/const_hexdig.patch
new file mode 100644
index 0000000000000000000000000000000000000000..1a3145a8027a4cfe6640b1ad442f69962658625a
--- /dev/null
+++ b/base/third_party/dmg_fp/const_hexdig.patch
@@ -0,0 +1,13 @@
+diff --git a/base/third_party/dmg_fp/dtoa.cc b/base/third_party/dmg_fp/dtoa.cc
+index d7e6826..be560bc 100644
+--- a/base/third_party/dmg_fp/dtoa.cc
++++ b/base/third_party/dmg_fp/dtoa.cc
+@@ -1533,7 +1533,7 @@ hexdig_init(void)	/* Use of hexdig_init omitted 20121220 to avoid a */
+ 	htinit(hexdig, USC "ABCDEF", 0x10 + 10);
+ 	}
+ #else
+-static unsigned char hexdig[256] = {
++static const unsigned char hexdig[256] = {
+ 	0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
+ 	0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
+ 	0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,