This fixes an installer that passes to InstallProduct a command line like
PROPERTY1="Installing ""Product name"" version 8.0" PROPERTY2=1 PROPERTY3=1
In this case properties PROPERTY2 and PROPERTY3 were not recognized and that
led to an installation failure when a custom action didn't see them as set.
Signed-off-by: Dmitry Timoshkov <dmitry@baikal.ru>