explicitly specify Fortran compiler for recent CDO versions to fix issues on non-x86_64 architectures

[bedroge]

For EESSI we ran into an issue when building CDO on Arm CPUs (also see EESSI/software-layer#427 (comment)):

cfortran.h:193:2: warning: #warning "Please specify the fortran compiler using -D flags. Try to guess the compiler used" [-Wcpp]
  193 | #warning "Please specify the fortran compiler using -D flags. Try to guess the compiler used"
      |  ^~~~~~~
cfortran.h:265:2: error: #error "cfortran.h:  Can't find your environment among:    - GNU gcc (gfortran) on Linux.                                           - MIPS cc and f7
7 2.0. (e.g. Silicon Graphics, DECstations, ...)         - IBM AIX XL C and FORTRAN Compiler/6000 Version 01.01.0000.0000         - VAX   VMS CC 3.1 and FORTRAN 5.4.        
                              - Alpha VMS DEC C 1.3 and DEC FORTRAN 6.0.                               - Alpha OSF DEC C and DEC Fortran for OSF/1 AXP Version 1.2           
   - Apollo DomainOS 10.2 (sys5.3) with f77 10.7 and cc 6.7.                - CRAY                                                                   - NEC SX-4 SUPER-UX     
                                                 - CONVEX                                                                 - Sun                                              
                      - PowerStation Fortran with Visual C++                                   - HP9000s300/s700/s800 Latest test with: HP-UX A.08.07 A 9000/730        - Lyn
xOS: cc or gcc with f2c.                                            - VAXUltrix: vcc,cc or gcc with f2c. gcc or cc with f77.                 -            f77 with vcc works;
 but missing link magic for f77 I/O.     -            NO fort. None of gcc, cc or vcc generate required names.    - f2c/g77:   Use #define    f2cFortran, or cc -Df2cFortran 
              - gfortran:  Use #define    gFortran,   or cc -DgFortran                              (also necessary for g77 with -fno-f2c option)               - NAG f90: Us
e #define NAGf90Fortran, or cc -DNAGf90Fortran              - Absoft UNIX F77: Use #define AbsoftUNIXFortran or cc -DAbsoftUNIXFortran     - Absoft Pro Fortran: Use #define 
AbsoftProFortran     - Portland Group Fortran: Use #define pgiFortran     - Intel Fortran: Use #define INTEL_COMPILER"
  265 | #error "cfortran.h:  Can't find your environment among:\
      |  ^~~~~

CDO's configure script does have some logic that sets -DgFortran on x86_64 Linux systems, but it doesn't do this for aarch64. This PR explicitly adds this flag to $CPPFLAGS for recent CDO versions, which resolves the issue.

[bedroge]

@boegelbot please test @ generoso

[boegelbot]

@bedroge: Request for testing this PR well received on login1

PR test command 'EB_PR=19735 EB_ARGS= EB_CONTAINER= EB_REPO=easybuild-easyconfigs /opt/software/slurm/bin/sbatch --job-name test_PR_19735 --ntasks=4 ~/boegelbot/eb_from_pr_upload_generoso.sh' executed!

• exit code: 0
• output:

Submitted batch job 12756

Test results coming soon (I hope)...

- notification for comment with ID 1912678023 processed

Message to humans: this is just bookkeeping information for me,
it is of no use to you (unless you think I have a bug, which I don't).

[boegelbot]

Test report by @boegelbot
SUCCESS
Build succeeded for 4 out of 4 (4 easyconfigs in total)
cns1 - Linux Rocky Linux 8.5, x86_64, Intel(R) Xeon(R) CPU E5-2667 v3 @ 3.20GHz (haswell), Python 3.6.8
See https://gist.github.com/boegelbot/6c00341093348b268689ab05ccbc1bab for a full test report.

[bedroge]

@boegelbot please test @ jsc-zen3

[bedroge]

All builds with the EESSI bot for CDO 2.2.2 from this PR have succeeded as well, for 5 x86_64 CPUs and 3 aarch64 CPUs: EESSI/software-layer#427 (comment).

[boegelbot]

@bedroge: Request for testing this PR well received on jsczen3l1.int.jsc-zen3.fz-juelich.de

PR test command 'if [[ develop != 'develop' ]]; then EB_BRANCH=develop ./easybuild_develop.sh 2> /dev/null 1>&2; EB_PREFIX=/home/boegelbot/easybuild/develop source init_env_easybuild_develop.sh; fi; EB_PR=19735 EB_ARGS= EB_CONTAINER= EB_REPO=easybuild-easyconfigs EB_BRANCH=develop /opt/software/slurm/bin/sbatch --job-name test_PR_19735 --ntasks=8 ~/boegelbot/eb_from_pr_upload_jsc-zen3.sh' executed!

• exit code: 0
• output:

Submitted batch job 3496

Test results coming soon (I hope)...

- notification for comment with ID 1912734590 processed

Message to humans: this is just bookkeeping information for me,
it is of no use to you (unless you think I have a bug, which I don't).

[ocaisa]

LGTM

[boegelbot]

Test report by @boegelbot
SUCCESS
Build succeeded for 10 out of 10 (4 easyconfigs in total)
jsczen3c1.int.jsc-zen3.fz-juelich.de - Linux Rocky Linux 9.3, x86_64, AMD EPYC-Milan Processor (zen3), Python 3.9.18
See https://gist.github.com/boegelbot/06305579c557b4c3d2c3af3b2c68be9a for a full test report.