Add -rdynamic to ezmlm-idx's conf-ld. This flag was added in ezmlm-idx
7.2.2 and is necessary in order for ezmlm to work on FreeBSD 12; but it
was being removed when we overwrote conf-ld. 
While I'm here, remove the djbware "no license" LEGAL_TEXT, which was
added in error several years ago; this package is GPLv2.
Reported by: Matt Simerson
Approved by: ports-secteam (blanket: run bugfixes)
Reminded by: koobs