Revert rC349281 '[analyzer][MallocChecker][NFC] Document and reorganize some functions'

Accidentally commited earlier with the same commit title, but really it
should've been
"Revert rC349283 '[analyzer][MallocChecker] Improve warning messages on double-delete errors'"


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@349344 91177308-0d34-0410-b5e6-96231b3b80d8