Convert cvsignore to gitignore, and add .gitignore for build targets.

src/bin/pg_ctl/.gitignore

src/bin/pg_dump/.gitignore

src/bin/pg_resetxlog/.gitignore

src/bin/psql/.cvsignore

src/bin/psql/.gitignore

src/bin/scripts/.gitignore

src/include/.gitignore

src/include/catalog/.gitignore

src/include/parser/.gitignore

src/include/utils/.gitignore

src/interfaces/ecpg/compatlib/.cvsignore

src/interfaces/ecpg/compatlib/.gitignore

src/interfaces/ecpg/ecpglib/.cvsignore

src/interfaces/ecpg/ecpglib/.gitignore

src/interfaces/ecpg/include/.gitignore

src/interfaces/ecpg/pgtypeslib/.cvsignore

src/interfaces/ecpg/pgtypeslib/.gitignore

src/interfaces/ecpg/preproc/.cvsignore

src/interfaces/ecpg/preproc/.gitignore

src/interfaces/libpq/.cvsignore