io: Handle long lines

As an APKINDEX can become arbitrarely long due to dependencies and
other parameters, increasing the buffer size make this less likely
to happens.

Closes #10731.

src/io.c

@@ -32,7 +32,7 @@
 #define HAVE_FGETGRENT_R
 #endif
 
-size_t apk_io_bufsize = 8*1024;
+size_t apk_io_bufsize = 16*1024;
 
 static void apk_file_meta_from_fd(int fd, struct apk_file_meta *meta)
 {