a collection of changes to ensure the fortran code compiles with gfortran v10.0

[jdkloe]

Note that the code compiles but not all tests pass, so some additional work will be needed before this gfortran version can be used.

[FussyDuck]

All committers have signed the CLA.

[shahramn]

Dear Jos
Can you tell us precisely which tests fail?

[jdkloe]

Dear Jos
Can you tell us precisely which tests fail?

Sure. I see the following 4 tests fail after applying these patches and running the tests:

The following tests FAILED:
179 - eccodes_f_grib_copy_message (Failed)
180 - eccodes_f_bufr_copy_message (Failed)
198 - eccodes_f_read_message (Failed)
199 - eccodes_f_read_from_file (Failed)
Errors while running CTest

For your reference I also attached the logging output of the 4 test cases when I run them with extra verbosity like this:
ctest -VV -debug -R "eccodes_f_grib_copy_message|eccodes_f_bufr_copy_message|eccodes_f_read_message|eccodes_f_read_from_file" > log.txt 2>1
eccodes_2.15.0_failing_tests_gfortran_v10.txt.gz
Two of them show an ugly segmentation fault, and 2 others seem not ably to detect the 7777 code at the end of the grib message.