cmake BOOST_FILESYSTEM_HAS_FALLOCATE examples

Jackarain/proxy third_party/boost/libs/filesystem/CMakeLists.txt :51 

check_cxx_source_compiles("#include <${CMAKE_CURRENT_SOURCE_DIR}/config/has_fallocate.cpp>" BOOST_FILESYSTEM_HAS_FALLOCATE)

Jackarain/proxy third_party/boost/libs/filesystem/CMakeLists.txt :225 

target_compile_definitions(boost_filesystem PRIVATE BOOST_FILESYSTEM_HAS_FALLOCATE)