* Add support for bsd.port.options.mk. [1]
* Add a check for ports that install a.out. [2]
* Tweak the check for arguments passed to configure when using
GNU_CONFIGURE, and add a check for HAS_CONFIGURE and GNU_CONFIGURE. [3]
* Fix some false positives that occur when using certain combinations of
%%XXXDIR%%. [4]
PR: 135095 [2]
135858 [3]
136465 [4]
Requested by: pav [1]
Submitted by: Vladimir Chukharev <chukharev@mail.ru> [2]
Sahil Tandon <sahil@tandon.net> [3]
Eygene Ryabinkin <rea-fbsd@codelabs.ru> [4]
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