Message style review

src/interfaces/ecpg/preproc/descriptor.c

src/interfaces/ecpg/preproc/ecpg.addons

src/interfaces/ecpg/preproc/ecpg.c

src/interfaces/ecpg/preproc/ecpg.header

src/interfaces/ecpg/preproc/ecpg.trailer

src/interfaces/ecpg/preproc/pgc.l

src/interfaces/ecpg/preproc/type.c

src/interfaces/ecpg/preproc/variable.c