cmake HAVE_FLEXIBLE_ARRAY examples

Sneeds-Feed-and-Seed/sneedacity cmake-proxies/libsndfile/CMakeLists.txt :171 

try_compile( HAVE_FLEXIBLE_ARRAY
   ${CMAKE_CURRENT_BINARY_DIR}
   ${_SRCDIR}/famcheck.c
   LINK_LIBRARIES ${CMAKE_REQUIRED_LIBRARIES}
   OUTPUT_VARIABLE c_out
)