Fix comparison of flags with multiple bits set.

Fix comparison of flags with multiple bits set.

PGPENCRYPT, PGPKEY, SMIMEENCRYPT, and SMIMEOPAQUE are all combination
flags, with multiple bits set.  In a few places these flags were
bitwise-and'ed incorrectly: expecting a non-zero result to indicate
all the bits in the flag were set.  Change those to explicitly compare
the result against the original flag.