This makes sure we don't generate a lot of code to spill/reload
CSRs when calling tls_init from the access functions.

This helps performance when tls_init is not inlined into the access
functions.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@263854 91177308-0d34-0410-b5e6-96231b3b80d8