build: fix __builtin_expect detection for clang #145

1. 
   theuni commented at 0:08 am on December 9, 2014: contributor

   Using AC_CHECK_DECL, the generated test tries to cast the function to void. Clang doesn’t allow that for builtins.
2. 
   jgarzik commented at 0:09 am on December 9, 2014: none

   ut ACK
3. 
   sipa commented at 0:32 am on December 9, 2014: contributor

   ACK if Travis happy.
4. 
   sipa commented at 1:35 am on December 9, 2014: contributor

   Rebase, so this gets tested on top of #144?
5. theuni force-pushed on Dec 9, 2014
6. build: fix __builtin_expect detection for clang

   Using AC_CHECK_DECL, the generated test tries to cast the function to void.
   Clang doesn't allow that for builtins.

   1f46b006b7
7. 
   theuni commented at 3:42 am on December 9, 2014: contributor

   done
8. 
   gmaxwell commented at 9:56 am on December 9, 2014: contributor

   ACK
9. sipa merged this on Dec 9, 2014
10. sipa closed this on Dec 9, 2014

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11. sipa referenced this in commit 9000458677 on Dec 9, 2014

Contributors
theuni jgarzik sipa gmaxwell