title: No support to -finline-functions in clang 3.5?
body: <p>I am using clang 3.5 as distributed by them. I'm using the following command lines to install it in my travis vm:</p>
  
  <pre><code>sudo apt-add-repository 'deb http://llvm.org/apt/precise/ llvm-toolchain-precise-3.5 main'
  sudo apt-add-repository 'deb http://llvm.org/apt/precise/ llvm-toolchain-precise-3.5 main'
  </code></pre>
  
  <p>When I run my test build with optimizations turned on, I get this error: </p>
  
  <pre><code>clang: error: optimization flag '-finline-functions' is not supported
    "clang++" -c -x c++ -std=c++1y -Werror -O3 -finline-functions -Wno-inline -Wall -Werror -pthread -fPIC -std=c++1y -DBOOST_ALL_DYN_LINK -DNDEBUG -I"." -I"gamgee" -I"lib/htslib" -o "test/bin/run.test/clang-linux-3.5.0/release/threading-multi/sam_builder_test.o" "test/sam_builder_test.cpp"
  </code></pre>
  
  <p>I don't get the same error on my mac which runs the older 3.4 version of clang. </p>
  
  <p>Has clang cut support to -finline-functions in 3.5? Is this something specific about this package build? How should one substitute the -finline-functions option for optimized builds with clang-3.5+? </p>