Change for building dtoa on 64-bit.

base/third_party/dmg_fp/gcc_64_bit.patch

Index: base/third_party/dmg_fp/gcc_64_bit.patch
diff --git a/base/third_party/dmg_fp/gcc_64_bit.patch b/base/third_party/dmg_fp/gcc_64_bit.patch
new file mode 100644
index 0000000000000000000000000000000000000000..ab943c08ee6434eddb9474e1dbb152401729838b
--- /dev/null
+++ b/base/third_party/dmg_fp/gcc_64_bit.patch
@@ -0,0 +1,25 @@
+Index: dtoa.cc
+--- dtoa.cc    (old copy)
++++ dtoa.cc    (working copy)
+@@ -183,8 +183,12 @@
+ #define NO_HEX_FP
+ 
+ #ifndef Long
++#if __LP64__
++#define Long int
++#else
+ #define Long long
+ #endif
++#endif
+ #ifndef ULong
+ typedef unsigned Long ULong;
+ #endif
+@@ -221,7 +225,7 @@ extern void *MALLOC(size_t);
+ #ifndef PRIVATE_MEM
+ #define PRIVATE_MEM 2304
+ #endif
+-#define PRIVATE_mem ((PRIVATE_MEM+sizeof(double)-1)/sizeof(double))
++#define PRIVATE_mem ((unsigned)((PRIVATE_MEM+sizeof(double)-1)/sizeof(double)))
+ static double private_mem[PRIVATE_mem], *pmem_next = private_mem;
+ #endif
+