Remove obsolete compatibility links

* /usr/bin/strip would be replaced by a link, even when compiling
    binutils.
 * Updated minix-spec.h to use the correct dynamic linker, and removed
    the previously used symlinks.
 * Removed the patch to the builtin PATH of ld.elf_so.

Change-Id: I4dc8a7fb77a11638f5105a4e15b6c9be5add750e

etc/mtree/NetBSD.dist.base

@@ -25,7 +25,6 @@
 ./etc/system.conf.d
 ./home
 ./lib
-./libexec
 ./mnt
 ./proc
 ./root