Revert "Made 'make install' include libs for additional targets"

This reverts commit 87334fb05ff2a665419241d877c13d6c4770a3f4.

Conflicts:
	mk/install.mk
configure: Add --enable-dist-host-only flag

This preserves the current behavior of `make dist` where we only
distribute bins for the host architecture. The bots need this.
mk: Have the various flavors of 'dist' install all targets by default

Closes #15711
auto merge of #15928 : brson/rust/dist, r=alexcrichton,alexcrichton

The first commit reverts a similar fix that only solves the `make install` case. This adds the `--enable-dist-host-only` flag to configure to preserve the old behavior, which the nightly bots rely on. The bots will need to be updated soon after this lands (or they will ~double in size).

Closes https://github.com/rust-lang/rust/issues/15711