travis: add clang to the test matrix #144

1. 
   theuni commented at 10:01 pm on December 8, 2014: contributor

   simple enough.
2. travis: add clang to the test matrix 992e03bc28
3. 
   sipa commented at 0:44 am on December 9, 2014: contributor

   ACK
4. sipa merged this on Dec 9, 2014
5. sipa closed this on Dec 9, 2014

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6. sipa referenced this in commit 8a0775cfaf on Dec 9, 2014
7. sipa cross-referenced this on Dec 9, 2014 from issue build: fix __builtin_expect detection for clang by theuni

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theuni sipa