Update to 2015.1/1171507 and remove exec statements.

[mat]

devel/p4d/Makefile

46–48

We try to keep the targets in the order they're run, so that it's easier to read, so, in theory, this one should go after do-install.
Now, there's no need to have two targets, so just add the MKDIR to the do-install target.

[gordon]

Move stage to install.
Use common variables migrated to p4/Makefile.inc

[gordon]

Committed as 392477.