add buildout file for llvm and clang

component/llvm/buildout.cfg

+[buildout]
+extends = 
+  ../cmake/buildout.cfg
+  
+parts = 
+  llvm-make
+
+[llvm]
+recipe = hexagonit.recipe.download
+url = http://llvm.org/releases/3.5.2/llvm-3.5.2.src.tar.xz
+md5sum = f5a4dc595f7e8bd23397684d0906d014
+destination = ${buildout:parts-directory}
+path = ${buildout:parts-directory}/llvm-3.5.2.src
+
+[clang]
+recipe = hexagonit.recipe.download
+url = http://llvm.org/releases/3.5.2/cfe-3.5.2.src.tar.xz
+filename = cfe-3.5.2.src.tar.xz
+md5sum = aba5d02251bf7845a2013d6bb0702ac7
+destination = ${llvm:path}/tools
+path = ${llvm:path}/tools/cfe-3.5.2.src
+
+[llvm-cmake]
+recipe = slapos.recipe.cmmi
+# clang have to put in llvm/tools/clang dir
+# and cannot build in place. So use cmake undocumented feature(-B, -H)
+# to specify the source code path and build path
+configure-command = $ [ -d ${:tools-clang} ] && rm -R ${:tools-clang} ||
+  mv ${clang:path} ${:tools-clang} && \
+  ${cmake:location}/bin/cmake \
+  -B${buildout:parts-directory}/llvm-cmake \
+  -H${llvm:path} \
+  -DCMAKE_INSTALL_PREFIX=${:location}
+
+tools-clang = ${llvm:path}/tools/clang
+path = ${buildout:parts-directory}/llvm-cmake
+location = ${buildout:parts-directory}/llvm
+
+[llvm-make]
+recipe = slapos.recipe.cmmi
+path = ${llvm-cmake:path}
\ No newline at end of file