qtbase: Fix build error on 64bit BigEndian platforms

The functions fromBytesToWord() and fromWordToBytes() are called when
building on 64bit BigEndian platforms. It fails because those
functions are disabled on the source code. Enabling those functions for
64bit BigEndian platforms fixes the problem.

Task-number: QTBUG-35228

Change-Id: I5ccacd4fb5051df05f67c8da879b3a9e49953861
Signed-off-by: Vicente Olivert Riera <Vincent.Riera@imgtec.com>
Reviewed-by: Giuseppe D'Angelo <giuseppe.dangelo@kdab.com>
Reviewed-by: Richard J. Moore <rich@kde.org>

src/3rdparty/sha3/KeccakF-1600-opt64.c

@@ -328,7 +328,7 @@ static void KeccakPermutation(unsigned char *state)
     KeccakPermutationOnWords((UINT64*)state);
 }
 
-#if 0 // Unused in the Qt configuration
+#if (PLATFORM_BYTE_ORDER == IS_BIG_ENDIAN)
 static void fromBytesToWord(UINT64 *word, const UINT8 *bytes)
 {
     unsigned int i;
@@ -449,7 +449,7 @@ static void KeccakAbsorb(unsigned char *state, const unsigned char *data, unsign
 #endif
 }
 
-#if 0 // Unused in the Qt configuration
+#if (PLATFORM_BYTE_ORDER == IS_BIG_ENDIAN)
 static void fromWordToBytes(UINT8 *bytes, const UINT64 word)
 {
     unsigned int i;