Merge #1625: util: Remove unused (u)int64_t formatting macros

980c08d util: Remove unused (u)int64_t formatting macros (Tim Ruffing)

Pull request description:

  We should anyway prefer to use the predefined macros from <inttypes.h>.

  If I haven't missed anything, this removes the last OS-specific #if, leaving us only with compiler-specific #if(def)s.

ACKs for top commit:
  theStack:
    utACK 980c08d

Tree-SHA512: bcfc962618c6d0343c8231f9ea5ca23029b4e4946c4239cd9732933fe7065963d7c0ef2db60f72b76e0721865a61b8a9957b62398bb2d0b8f6bbc1d25461f1b3

src/util.h

@@ -192,14 +192,6 @@ static SECP256K1_INLINE void *checked_malloc(const secp256k1_callback* cb, size_
 # endif
 #endif
 
-#if defined(_WIN32)
-# define I64FORMAT "I64d"
-# define I64uFORMAT "I64u"
-#else
-# define I64FORMAT "lld"
-# define I64uFORMAT "llu"
-#endif
-
 #if defined(__GNUC__)
 # define SECP256K1_GNUC_EXT __extension__
 #else