Went down the list in shmkeys.h, added sane error msgs on perms
errors accessing rest of the shmsegs there.
Realized we probably do need 666 to the shmsegs.
Also deleted a little dead code that was copy-pasted everywhere.
This patch catches exceptions in DDLProc, DMLProc and ExeMgr which could
potentially happen during startup. Logging them instead of silently
ignoring them (or crashing in ExeMgr).
This does the following:
* Switch resource manager to a singleton which reduces the amount of
times the XML data is scanned and objects allocated.
* Make the I_S tables use the FE implementation of the system catalog
* Make the I_S.columnstore_columns table use the RID list cache
* Make the extentmap pre-allocate a vector instead of many small allocs
