CC Mode: Eliminate compiler warning messages.

CC Mode: Eliminate compiler warning messages.

* lisp/progmodes/cc-mode.el (top level): remove compile time declaration of
`font-lock-syntactic-keywords' (which CC Mode doesn't use).
* lisp/progmodes/cc-awk.el (awk-mode-syntax-table)
(c-awk-set-syntax-table-properties): Clarify comments about
`font-lock-syntactic-keywords'.

* lisp/progmodes/cc-bytecomp.el (cc-bytecomp-load): Create a dummy declaration
of this before the real (interpreted) one, to satisfy the byte compiler.