mk: Remove leading './' from manifest entries
Revert "Revert "mk: Run 'make install' through install.sh""

This reverts commit d62163188a21e5afc3d0f476eaf7856d91f715b2.

Conflicts:
	mk/install.mk
configure: Make rustlibdir non-configurable

Trying to reduce the complexity of installation
rustc: Stop relying on CFG_LIBDIR_RELATIVE

This is not sufficient for finding the library directory for binary
installs, but it does make the build more complex by requiring
env vars be set to build rustc.
mk: Rename CFG_COMPILER to CFG_COMPILER_HOST_TRIPLE

Much clearer