lib/util_hash: revert change to FILE stream.

It makes tests fail like crazy. Investigate.

lib/util_hash.c

@@ -111,8 +111,8 @@ xbps_mmap_file(const char *file, void **mmf, size_t *mmflen, size_t *filelen)
 bool
 xbps_file_sha256_raw(unsigned char *dst, size_t dstlen, const char *file)
 {
-	FILE *stream;
-	size_t len;
+	int fd;
+	ssize_t len;
 	char buf[65536];
 	br_sha256_context sha256;
 
@@ -122,17 +122,17 @@ xbps_file_sha256_raw(unsigned char *dst, size_t dstlen, const char *file)
 		return false;
 	}
 
-	if ((stream = fopen(file, "r")) == 0)
+	if ((fd = open(file, O_RDONLY)) < 0)
 		return false;
 
 	br_sha256_init(&sha256);
 
-	while ((len = fread(buf, 1, sizeof(buf), stream)) == sizeof(buf))
+	while ((len = read(fd, buf, sizeof(buf))) > 0)
 		br_sha256_update(&sha256, buf, len);
 
-	fclose(stream);
+	close(fd);
 
-	if(len == 0)
+	if(len == -1)
 		return false;
 
 	br_sha256_out(&sha256, dst);