Fix most memory leaks in tablegen.

Found by the valgrind bot.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@193736 91177308-0d34-0410-b5e6-96231b3b80d8
Fix a use after free on invalid input.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@193737 91177308-0d34-0410-b5e6-96231b3b80d8