Feature request: Make debug build optional and/or fix BTF debug info issue

[simonhf]

Currently the -g flag is set everywhere during building. This can cause a BTF issue [1] if the source file referenced in the BTF section cannot be found at clang compiled BPF load time.

It would be great if the Makefile somehow allowed for a non-debug version to be built as a workaround.

But it would also be great if the BTF error [1] was clearer at run-time, and/or allowed a path to be specified to the source files in order to override the path in the BTF section, in case the source file are in a different location at run-time.

[1] https://github.com/xdp-project/xdp-tutorial/issues/38#issuecomment-662181960