Replace Makefile.lib32 with generalized Makefile.libcompat.

[bdrewery]

Summary

It only supports 1 libcompat type so far. No looping or multi-inclusion
supported yet since we don't need that.

Test Plan

Running buildworld now

[bdrewery]

Make this a diff against Makefile.lib32

[bdrewery]

Meant to have Makefile.inc1 not Makefile

[bdrewery]

Makefile.libcompat

44 ↗

(On Diff #14248)

I would leave out this section and let you commit it with D5605

[bdrewery]

• Fix LIB32TMP / LIB32WMAKE references by generalizing more. This makes most of D5605 not needed. It now only needs to add the logic to include Makefile.libcompat with LIBCOMPAT=SOFT and add the right bits to Makefile.libcompat.

[bdrewery]

Fix more invalid references to removed LIB32*

[bdrewery]

Fix LIBCOMPATTMP and LIBCOMPAT_OBJTREE being empty, leading to wrong compiler and no DESTDIR during build.

[bdrewery]

Fix use of empty() - no real change though as it was properly set before this

[bdrewery]

With the latest version buildworld/installworld seem fine and nothing is leaking outside of DESTDIR.