Update to p4 2015.1/1126382

[gordon]

Accidentally forgot to update my local svn before generating the diff.

[mat]

devel/p4/Makefile

20–22

As they seem to be the same for every port, I wonder if those three lines should not go in the Makefile.inc. with a ?= in case one needs to override them.

[gordon]

Incorporate feedback to move common lines into the Makefile.inc

[gordon]

Committed as 392478.