Rename variables in ada-lang.c:ada_make_symbol_completion_list.

Rename variables in ada-lang.c:ada_make_symbol_completion_list.

This renaming allows us to have variable names that are consistent
with the names of the parameters in the functions where these
variables are used.  This also allows us to avoid a -Wshadow warning
in the case of variable "wild_match", which is now renamed to
"wild_match_p".

gdb/ChangeLog:

        -Wshadow warning fix.
        * ada-lang.c (ada_make_symbol_completion_list): Rename parameters
        "wild_match" and "encoded" into "wild_match_p" and "encoded_p".
        Adjust code accordingly.