Merge *history only* from branch 'luajit/v2.1' commit fd37da0 into pu…

…ll-luajit

This merge is created with 'git merge -s ours' to keep the existing
RaptorJIT code while merging in the commit IDs from LuaJIT.

Invariant: Each commit-id merged repreents a change that has been
"processed" and should not need to be considered again. "Processed"
means either cherry picked (for changes we want in RaptorJIT) or
ignored (for changes we don't want.)