[openssl.org #2454] enable engine key for dsa command

Obsolete code prevent dsa command to use keys stored into engine. The attached patch remove open of input file and left all to load_xxx functions. See for reference rsa command that work fine. Roumen Index: apps/dsa.c === RCS file:

[openssl.org #2455] print dsa pubin/pubout options

See attached file with patch for openssl dsa command: print -pubin/-pubout options. Also -engine flags is moved at same position as for rsa command. Roumen Index: apps/dsa.c === RCS file: