Merge pull request libgit2#5107 from pks-t/pks/sha1dc-update

sha1dc: update to fix endianess issues on AIX/HP-UX

Author: ethomson

src/hash/sha1dc/sha1.c

@@ -93,13 +93,23 @@
 #define SHA1DC_BIGENDIAN
 
 /* Not under GCC-alike or glibc or *BSD or newlib or <processor whitelist> */
+#elif (defined(_AIX) || defined(__hpux))
+
+/*
+ * Defines Big Endian on a whitelist of OSs that are known to be Big
+ * Endian-only. See
+ * https://public-inbox.org/git/93056823-2740-d072-1ebd-46b440b33d7e@felt.demon.nl/
+ */
+#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)
 /*
  * As a last resort before we do anything else we're not 100% sure
  * about below, we blacklist specific processors here. We could add
  * more, see e.g. https://wiki.debian.org/ArchitectureSpecificsMemo
  */
-#else /* Not under GCC-alike or glibc or *BSD or newlib or <processor whitelist>  or <processor blacklist> */
+#else /* Not under GCC-alike or glibc or *BSD or newlib or <processor whitelist> or <os whitelist> or <processor blacklist> */
 
 /* We do nothing more here for now */
 /*#error "Uncomment this to see if you fall through all the detection"*/
@@ -114,10 +124,11 @@
 #endif
 /*ENDIANNESS SELECTION*/
 
+#ifndef SHA1DC_FORCE_ALIGNED_ACCESS
 #if defined(SHA1DC_FORCE_UNALIGNED_ACCESS) || defined(SHA1DC_ON_INTEL_LIKE_PROCESSOR)
 #define SHA1DC_ALLOW_UNALIGNED_ACCESS
-#endif /*UNALIGNMENT DETECTION*/
-
+#endif /*UNALIGNED ACCESS DETECTION*/
+#endif /*FORCE ALIGNED ACCESS*/
 
 #define rotate_right(x,n) (((x)>>(n))|((x)<<(32-(n))))
 #define rotate_left(x,n)  (((x)<<(n))|((x)>>(32-(n))))