[QA][5.5] difference between rpm tags, INSTALLPREFIX and INSTPREFIXES

Issue

• On RHEL5, 2 tags, INSTALLPREFIX and INSTPREFIXES, similar to each other are available for the rpm command.  But we don't know exactly what the difference between those is.

• Partner's middleware has been using INSTALLPREFIX in his own script on RHEL5, but we know that the tag is not available for the rpm command on RHEL6. 

• Partner needs to know whether INSTPREFIXES similar to the said tag can be used in the script on RHEL6 instead.