Whittle away at warnings: (#32397)

Whittle away at warnings: (#32397)

Whittle away at warnings:
 Return address of local (deliberate).
 Pointer cast to different size.
 Function parameter and declaration badly mismatch (pid_t vs. void*).
 Unused locals.
 Top level volatile is ignored.
 Negative shift undefined.
 Call to undeclared function (getpid).

Some are fixed, some are disabled temporarily.

Co-authored-by: Jay Krell <jay.krell@cornell.edu>