/bin to /usr/bin questions

[jeremyd2019]

(commits as of 3.5.7)
Commit d47d052 switches Cygwin's behavior of making /usr/bin an alias of /bin, to making /bin an alias of /usr/bin. As part of that, it dropped the /usr/lib alias of /lib. Later, 1650471 changed the default path to the shell to be under /usr/bin.

After the breakage building ksh93, I have a couple of questions

1. Should we have a bind mount of /lib to /usr/lib, so that for instance gcc can find its files if invoked from bin?
2. Should we consider changing the _CS_PATH confstr constant to /usr/bin:/bin? I think this would have made ksh93 happy, but Linux also seems to return /bin:/usr/bin for this, so perhaps it could have unintended consequences?

   msys2-runtime/winsup/cygwin/sysconf.cc

   Line 662 in 7878787

   {ls ("/bin:/usr/bin")}, /* _CS_PATH */

[jeremyd2019]

I confirmed that changing _CS_PATH to return /usr/bin:/bin fixes the ksh93 build issue.