Make the crc32 big-endian computation use pointer post-increment like…

… the little-endian version was already doing

crc32.c

@@ -282,7 +282,7 @@ local unsigned long crc32_little(crc, buf, len)
 
 /* ========================================================================= */
 #define DOBIG4 \
-        memcpy(&bufword, ++buf4, sizeof(z_crc_t));    \
+        memcpy(&bufword, buf4++, sizeof(z_crc_t));    \
         c ^= bufword; \
         c = crc_table[4][c & 0xff] ^ crc_table[5][(c >> 8) & 0xff] ^ \
             crc_table[6][(c >> 16) & 0xff] ^ crc_table[7][c >> 24]
@@ -306,7 +306,6 @@ local unsigned long crc32_big(crc, buf, len)
     }
 
     buf4 = (const z_crc_t FAR *)(const void FAR *)buf;
-    buf4--;
     while (len >= 32) {
         DOBIG32;
         len -= 32;
@@ -315,7 +314,6 @@ local unsigned long crc32_big(crc, buf, len)
         DOBIG4;
         len -= 4;
     }
-    buf4++;
     buf = (const unsigned char FAR *)buf4;
 
     if (len) do {