Rename the cfguard module flag to cfguardtable

The previous name sounds like it inserts cfguard implementation, but it
really just emits the table of address-taken functions. Change the name
to better reflect that.

Clang will be updated in the next commit.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@339419 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed