Improve xmake.lua for android

[waruqi]

#228
#234

[waruqi]

I have improved elfutils package in xmake-repo. we need update it first.

xrepo update-repo
xrepo remove --all -y elfutils
xmake f -p android -c --require-bpftool=y
xmake

about elfutils issue:

This is because after the elfutils package in xmake-repo was installed, its make install script did not automatically install elf.h, so elfutils/libelf.h automatically found elf.h on the system, resulting in some header file conflicts.

see this patch: xmake-io/xmake-repo@e743cdc

[guri87-byte]

Thank you @waruqi

[anakryiko]

Great, thanks a lot for the fixes and improvements!