This reverts commit cfb81e4a00.

This reverts commit 32e7732061.

Due to `utils` module removal, `EXTERNAL_CONFIG_FLAGS` was not working, so the system was redesigned.
This change is independent of #4411

[utils] was created long time ago, when [rcore] contained all the platforms code, the purpose of the file was exposing basic filesystem functionality across modules and also logging mechanism but many things have changed since then and there is no need to keep using this module.

 - Logging system has been move to [rcore] module and macros are exposed through `config.h` to other modules
 - File system functionality has also been centralized in [rcore] module that along the years it was already adding more and more file-system functions, now they are all in the same module
 - Android specific code has been moved to `rcore_android.c`, it had no sense to have specific platform code in `utils`, [rcore] is responsible of all platform code.