- buildrequire gdbm-devel also on 11.4 to fix build

- Switch from buildrequires gpgme-devel to libgpgme-devel for 11.4
- Work around missing buildrequires of libgpgme-devel by adding
libassuan-devel for 11.4

- recommend smtp_daemon since mutt has builtin SMTP support

- Fix the orther sidebar patch as it is broken with MALLOC_CHECK=1
now static buffers are used instead (re)alloced arrays.

- fix build by removing Makefiles from contrib
- added missing %mime_database_post/%mime_database_postun

- modified desktop file so mutt can be used as the default mailto
handler