INSTALL - add notes for creating user pcp before make from source
INSTALL - add notes for creating user pcp before make from source

In response to bug http://oss.sgi.com/bugzilla/show_bug.cgi?id=1040
from Tomáš Dohnálek.

adfernandes/pcp,andyvand/cygpcpfans,mbaldessari/pcp,adfernandes/pcp,prasincs/pcp,tjanez/pcp,tjanez/pcp,aeg-aeg/pcpfans,wuliming/pcp,prasincs/pcp,wuliming/pcp,mbaldessari/pcp,mbaldessari/pcp,andyvand/cygpcpfans,tjanez/pcp,edwardt/pcp,tjanez/pcp,tjanez/pcp,aeg-aeg/pcpfans,adfernandes/pcp,wuliming/pcp,edwardt/pcp,adfernandes/pcp,aeg-aeg/pcpfans,prasincs/pcp,andyvand/cygpcpfans,wuliming/pcp,tjanez/pcp,andyvand/cygpcpfans,aeg-aeg/pcpfans,edwardt/pcp,mbaldessari/pcp,andyvand/cygpcpfans,andyvand/cygpcpfans,prasincs/pcp,wuliming/pcp,adfernandes/pcp,aeg-aeg/pcpfans,edwardt/pcp,aeg-aeg/pcpfans,andyvand/cygpcpfans,mbaldessari/pcp,edwardt/pcp,adfernandes/pcp,adfernandes/pcp,mbaldessari/pcp,wuliming/pcp,adfernandes/pcp,aeg-aeg/pcpfans,wuliming/pcp,prasincs/pcp,tjanez/pcp,edwardt/pcp,prasincs/pcp,aeg-aeg/pcpfans,tjanez/pcp,wuliming/pcp,edwardt/pcp,andyvand/cygpcpfans,edwardt/pcp,prasincs/pcp,prasincs/pcp