K 10
svn:author
V 6
emaste
K 8
svn:date
V 27
2016-10-05T20:12:00.855995Z
K 7
svn:log
V 363
makeman: avoid bogus output with duplicated options

On some targets 'make showconfig' currently reports both 'no' and 'yes'
for some options. For example:

% make TARGET=mips showconfig | grep SSP
MK_SSP           = no
MK_SSP           = yes

Emit a warning on encountering a duplicated variable, and skip the
second entry.

Sponsored by:	The FreeBSD Foundation

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