K 10
svn:author
V 3
mat
K 8
svn:date
V 27
2015-10-01T07:56:36.346958Z
K 7
svn:log
V 897
Fix opt_VARS premature expansion.

Due to the way .for loop work, opt_VARS was being expanded too early
evaluation, which made it impossible to use vars that are set/modifies
afterwards (such as PREFIX or PKGDIR)

Fix this by changing opt_VARS handling logic so that the right side is
not prematurely expanded:

- Loop not by words (each word here is single VAR=val / VAR+=val tuple)
  but by unique left sides of assignments (VAR, VAR+ here)
- Using the left side, extract all corresponding right sides and
  append/assign them to a variable

This changes the way this opt_VARS line work, which behavior is between
invalid and undefined:

opt_VARS= FOO=bar FOO=baz

Before it would end up with "FOO=baz", now it ends up with "FOO=bar baz"

Submitted by:	amdmi3
Reviewed by:	antoine, mat
Approved by:	my portmgr hat
Sponsored by:	Absolight
Differential Revision:	https://reviews.freebsd.org/D3729

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