Log Message:
seamonkey: update to 2.49.3

remove patches for security fixes now upstream.

seamonkey is now based on firefox 52.7.3 ESR.
SeaMonkey 2.49.3 shares most parts of the mail and news code with Thunderbird.
Please read the Thunderbird 52.7.0 release notes for specific changes and
security fixes in this release.

SeaMonkey-specific changes
seamonkey official linux builds are based on GTK3 (no change for us)