Rename according to changed functionality.

m4/acx_fc_real_size.m4 → m4/acx_fc_run_check_size.m4

-dnl acx_fc_real_size.m4 --- determine size of fortran real types
+dnl acx_fc_run_check_size.m4 --- determine size of Fortran types from run-time
+dnl                              inquiry
 dnl
-dnl Copyright  (C)  2010  Thomas Jahns <jahns@dkrz.de>
+dnl Copyright  (C)  2020  Thomas Jahns <jahns@dkrz.de>
 dnl
 dnl Version: 1.0
 dnl Keywords: configure configure.ac autotools fortran real size
@@ -35,19 +36,15 @@ dnl LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 dnl NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 dnl SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 dnl
-dnl Commentary:
-dnl
-dnl
-dnl
-dnl Code:
-dnl
 dnl
 dnl ACX_FORTRAN_RUN_CHECK_SIZEOF(TYPE,VAR,ACTION-IF-FOUND,ACTION-IF-NOT-FOUND,
 dnl                              OPTIONAL-PROLOGUE)
 dnl
-dnl sets VAR to the size or unavailable if supplied.
+dnl sets VAR to the size of TYPE or unavailable if supplied.
 dnl executes ACTION-IF-FOUND if the size can be found,
 dnl or ACTION-IF-NOT-FOUND if the size cannot be determined.
+dnl If compiling a declaration of TYPE needs additional declarations, use or
+dnl include statements, those can be supplied as OPTIONAL-PROLOGUE.
 dnl
 AC_DEFUN([ACX_FORTRAN_RUN_CHECK_SIZEOF],
   [AC_REQUIRE([ACX_C_CHAR_BITS])