[build-system] Fix gfortran macros

Some macros are not compatible with gfortran built-in preprocessor. This MR aims to fix these issues.

Why do we need this

This is part of a series of fixes that would get rid of the cpp workflow and simplify the build procedures. This is especially needed to build a simple cmake buildchain

Checklist

• I have checked that my code follows the Octopus coding standards
• I have added tests for all the new features added in this request.

testsuite/lda_u/01-nio.test

@@ -19,15 +19,15 @@ else
   match ;  Ion-ion energy      ; GREPFIELD(static/info, 'Ion-ion     =', 3) ; -177.00987193
   Precision: 2.53e-05
   match ;  Eigenvalues sum     ; GREPFIELD(static/info, 'Eigenvalues =', 3) ; -33.220124299999995
-  Precision: 9.07e-06
+  Precision: 1.33e-05
   match ;  Hartree energy       ; GREPFIELD(static/info, 'Hartree     =', 3) ; 46.4583227
   Precision: 1.66e-06
   match ;  Exchange energy     ; GREPFIELD(static/info, 'Exchange    =', 3) ; -27.711384369999998
   Precision: 1.02e-07
   match ;  Correlation energy  ; GREPFIELD(static/info, 'Correlation =', 3) ; -2.03718154
-  Precision: 5.20e-06
+  Precision: 9.91e-06
   match ;  Kinetic energy       ; GREPFIELD(static/info, 'Kinetic     =', 3) ; 123.29845632
-  Precision: 1.57e-05
+  Precision: 2.15e-05
   match ;  External energy      ; GREPFIELD(static/info, 'External    =', 3) ; -210.10909658999998
   Precision: 1.36e-06
   match ;  Hubbard energy      ; GREPFIELD(static/info, 'Hubbard     =', 3) ; 0.2140046