Do a little spring cleaning:

• Drop the note that we prefer -jumbo (community-enhanced) versions instead of vanilla JtR releases and accompanying PORTSCOUT knob, add a nota bene to handle this with next JtR version update
• Remove broken mirror (gd.tuwien.ac.at) from the MASTER_SITES
• Remove BROKEN_SSL knob, it should build fine after recent changes
• Shorten BROKEN_$arch messages and fix a minor typo there
• While Solar Designer recommends to pass JOHN_SYSTEMWIDE_HOME and JOHN_SYSTEMWIDE_EXEC overrides via command line, in practice it is easier and cleaner (avoids plenty of those `warning: missing terminating '"' character [-Winvalid-pp-token]'' messages during configure stage) to patch params.h' file in place, so do it
• For JOHN_SYSTEMWIDE=1, pass it via environment (as CFLAGS_EXTRA) instead of appending to global CFLAGS value
• GC `pfx2john' symlink (should've been part of r494924)