rtld's Makefile used to add -L${LIBDIR} to LDFLAGS when MK_TOOLCHAIN was
no. This was done as part of a change to fix building rtld with
MK_TOOLCHAIN == no (although I'm not sure this part was necessary).
In any case as of 5f2e84015d libc_pic.a is built independent of the
MK_TOOLCHAIN setting and the main part of the workaround has already
been removed. Remove the rest now.
This reverts commit c0f5aeb032.
Reviewed by: jrtc27
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D39938