Clarify style(9) WRT comments following #endif, #else.
Clarify style(9) WRT comments following #endif, #else.

The closing comment is required only for long conditionally defined
code sections, with the exception of lint cases.  Attempt to document
also the logic for using '!' before the SOMETIMESSOMETHGINGHERE.
The goal of these comments is to make complex cases more
comprehensible, not to require them in all cases.  The rules here are
derived from behavior used in 90+% of the kernel source code.

Reviewed by and discussed with:	jhb, bde, mike

jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase