cmake HAVE_FCONVERT examples

arkdb/inception configure.cmake :400 

CHECK_FUNCTION_EXISTS (fconvert HAVE_FCONVERT)

alibaba/AliSQL configure.cmake :505 

CHECK_FUNCTION_EXISTS (fconvert HAVE_FCONVERT)

Tokutek/mysql-5.5 configure.cmake :340 

CHECK_FUNCTION_EXISTS (fconvert HAVE_FCONVERT)