meson: Makefile: drop cov target
meson: Makefile: drop cov target

Coverage functionality is provided directly by meson so there is no need
to convert it into meson.

Signed-off-by: Pavel Hrdina <d4772d05997b8abf035041e3b4f4996380ea7e7a@redhat.com>
Reviewed-by: Ján Tomko <4cab11cfb98d3c937327354a78eb07dbb6ee2bc6@redhat.com>
Reviewed-by: Peter Krempa <2cf5c04c61aa466e4a47bfedc747d17279c72ffc@redhat.com>
Reviewed-by: Neal Gompa <8135daa3762340227c0c67f1c47ad07a127bd3a3@gmail.com>

zippy2/libvirt,nertpinx/libvirt,libvirt/libvirt,zippy2/libvirt,jfehlig/libvirt,jfehlig/libvirt,olafhering/libvirt,olafhering/libvirt,nertpinx/libvirt,jardasgit/libvirt,olafhering/libvirt,zippy2/libvirt,libvirt/libvirt,jardasgit/libvirt,crobinso/libvirt,nertpinx/libvirt,olafhering/libvirt,jardasgit/libvirt,crobinso/libvirt,jfehlig/libvirt,libvirt/libvirt,crobinso/libvirt,jfehlig/libvirt,libvirt/libvirt,zippy2/libvirt,jardasgit/libvirt,nertpinx/libvirt,jardasgit/libvirt,crobinso/libvirt,nertpinx/libvirt