Patched config file ESMC_Conf.h, replacing the original file.
June 24th 2019 by PY Barriat (ELIC - UCL)
--- esmf/build_config/Linux.gfortran.default/ESMC_Conf.h.orig 2018-03-07 00:33:07.000000000 +0100
+++ esmf/build_config/Linux.gfortran.default/ESMC_Conf.h      2019-06-24 17:06:57.735994948 +0200
@@ -31,6 +31,7 @@
 // Typedef to match the data type of the 'hidden' string length
 // argument that Fortran uses when passing CHARACTER strings.
 #if (__GNUC__ > 7)
+#include <cstddef>
 typedef size_t ESMCI_FortranStrLenArg;
 #else
 typedef int ESMCI_FortranStrLenArg;