Update the {fmt} library to fix the colision with C string.h header.

external/CppFormat/format.cc

@@ -25,7 +25,7 @@
  SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
-#include "format.h"
+#include "fmt/format.h"
 
 #include <string.h>
 

external/CppFormat/ostream.cc

@@ -25,7 +25,7 @@
  SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
-#include "ostream.h"
+#include "fmt/ostream.h"
 
 namespace fmt {
 

external/CppFormat/posix.cc

@@ -30,7 +30,7 @@
 # define _CRT_SECURE_NO_WARNINGS
 #endif
 
-#include "posix.h"
+#include "fmt/posix.h"
 
 #include <limits.h>
 #include <sys/types.h>