Fixed Fedora 22 package build failure.

Since MariaDB packages have absolute paths, they are marked as not relocatable
by setting CPACK_RPM_PACKAGE_RELOCATABLE. According to logics of recent CPackRPM
it is not enough: one needs to set CPACK_PACKAGE_RELOCATABLE additionally.

cmake/cpack_rpm.cmake

@@ -34,6 +34,7 @@ SET(CPACK_PACKAGE_FILE_NAME "${CPACK_RPM_PACKAGE_NAME}-${VERSION}-${RPM}-${CMAKE
 SET(CPACK_RPM_PACKAGE_RELEASE "1%{?dist}")
 SET(CPACK_RPM_PACKAGE_LICENSE "GPL")
 SET(CPACK_RPM_PACKAGE_RELOCATABLE FALSE)
+SET(CPACK_PACKAGE_RELOCATABLE FALSE)
 SET(CPACK_RPM_PACKAGE_GROUP "Applications/Databases")
 SET(CPACK_RPM_PACKAGE_URL "http://mariadb.org")
 SET(CPACK_RPM_PACKAGE_SUMMARY "MariaDB: a very fast and robust SQL database server")