Fix window close issues

Stop filtering out SC_CLOSE. 'X' button works more reliably, also alt-F4.
Remove minimize box from style.

Signed-off-by: Kevin Wasserman <kevin.wasserman@painless-security.com>

(cherry picked from commit 1b977a4e768b1a54ebffcecdf356e54e6fa86ce6)

https://github.com/krb5/krb5/commit/a8f8ebb4460eb7a1063350326eb223604ac0bd5c
Author: Kevin Wasserman <kevin.wasserman@painless-security.com>
Committer: Tom Yu <tlyu@mit.edu>
Commit: a8f8ebb4460eb7a1063350326eb223604ac0bd5c
Branch: krb5-1.10
 src/windows/leash/MainFrm.cpp |    6 +-----
 1 files changed, 1 insertions(+), 5 deletions(-)