Clean up minor compiler warnings.

src/backend/utils/adt/pg_locale.c

src/include/utils/pg_locale.h

src/interfaces/odbc/convert.c

src/interfaces/odbc/misc.c

src/interfaces/odbc/misc.h

src/interfaces/odbc/options.c

src/interfaces/odbc/pgtypes.c

src/interfaces/odbc/results.c