wmaker: make parsing on display name less prone to crash in SetupEnvironment (Coverity #50096)
When creating the environment variable for the sub-process that wmaker can
create, Coverity pointed that if was possible to crash if the name of the
display did not contain the ':', which is probably ok in most case, but we
can't be sure about what it could contain in special cases.
This patch adds a proper check so, at least, it would not crash if the case
were to arise.
Signed-off-by: Christophe CURIS <christophe.curis@free.fr>
Signed-off-by: Carlos R. Mafra <crmafra@gmail.com>