Support Darwin/PowerPC

--- mercurial/thirdparty/sha1dc/lib/sha1.c.orig	2023-04-11 20:39:20.000000000 +0000
+++ mercurial/thirdparty/sha1dc/lib/sha1.c
@@ -102,6 +102,10 @@
  */
 #define SHA1DC_BIGENDIAN
 
+#elif (defined(__APPLE__) && defined(__BIG_ENDIAN__) && !defined(SHA1DC_BIGENDIAN))
+/* older gcc compilers which are the default on Apple PPC do not define __BYTE_ORDER__ */
+#define SHA1DC_BIGENDIAN
+
 /* Not under GCC-alike or glibc or *BSD or newlib or <processor whitelist> or <os whitelist> */
 #elif defined(SHA1DC_ON_INTEL_LIKE_PROCESSOR)
 /*