[PATCH] Disable x86 tail call optimizations that jump through GOT

[Chih-Hung Hsieh]

Please review my new diff 4. This should allow tail call optimizations for protected and hidden symbols.
AFAIK, jump to those symbols do not use GOT.
On the other hand, I found some oddity about "sin" and "sin2" symbols in one test case,
which made me to use the strange condition:

  if (!(G && (.... || ...))) isTailCall = false;


http://reviews.llvm.org/D9799

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