LTP drop MUSL specific patch

["Petr Vorel" <petr.vorel@gmail.com>]

Hi Khem, Richard,

I'd like to replace MUSL specific patch
meta/recipes-extended/ltp/ltp/0001-build-Add-option-to-select-libc-implementation.patch
with just removing broken files. We use this in upstream CI for Alpine, I ported
it to Buildroot [2], where works well. It's better because it does allow to
handle MUSL without rebasing this patch.

I was looking into the docs, it looks to me that do_configure [3] might be good hook
to add it into. But it looks like by default it contains oe_runmake clean [4].
Or should I use different hook? And how to find the default content of chosen
hook? (if I need to extend it, I'll have to provide the original as well)

Thanks for info.

Kind regards,
Petr

[1] https://github.com/linux-test-project/ltp/blob/master/travis/alpine.sh#L35
[2] https://git.busybox.net/buildroot/tree/package/ltp-testsuite/ltp-testsuite.mk#n72
[3] https://www.yoctoproject.org/docs/2.5/dev-manual/dev-manual.html#new-dependencies
[4] https://www.yoctoproject.org/docs/2.5/ref-manual/ref-manual.html#ref-tasks-configure