Update md5.c

The read from data is promoted to int, and so the left shift by 24 in md5.c may cause signed overflow. This requires cast to an unsigned int:

B-Con#33

md5.c

@@ -40,7 +40,7 @@ void md5_transform(MD5_CTX *ctx, const BYTE data[])
 	// endian byte order CPU. Reverse all the bytes upon input, and re-reverse them
 	// on output (in md5_final()).
 	for (i = 0, j = 0; i < 16; ++i, j += 4)
-		m[i] = (data[j]) + (data[j + 1] << 8) + (data[j + 2] << 16) + (data[j + 3] << 24);
+		m[i] = (data[j]) + (data[j + 1] << 8) + (data[j + 2] << 16) + ((WORD)data[j + 3] << 24);
 
 	a = ctx->state[0];
 	b = ctx->state[1];