Qualify all pointers referring to string literals as `const`
Eliminate unused local variables
Add missing local function prototypes.

Update all block comments for OSAL functions to follow a
consistent style and ensure correctness of the descriptions.

- All documentation covering the specific details, inputs/outputs
and return values should be on the function _declaration_, not the
definition.

- The definition should also contain a block comment for visual
distinction in the source file, but should be brief and refer
back to the prototype/declaration for detail.  Any detail information
that was indicated only with the definition is moved to the
declaration.

- Add doxygen tags/markup to external/public API block comments
and expand the descriptions of these functions where needed.

- Add block comments to the internal API prototypes, but _not_
as doxygen tags/markup.  Note these functions are internal use,
not part of the public API, and are not necessarily intended
to be stable across OSAL releases like the public API is.

- Removed stray prototypes for functions where there was no
actual definition/implementation.

Reviewed and approved at 2019-09-25 CCB