tests: Disable fortran submodule test on old GCC versions
Need gcc 6.0 or newer:
project('submodule single level', 'fortran',
meson_version: '>= 0.50.0')
+fortc = meson.get_compiler('fortran')
+if fortc.get_id() == 'gcc' and fortc.version().version_compare('<6.0')
+ error('MESON_SKIP_TEST need gfortran >= 6.0 for submodule support')
+endif
+
hier2 = executable('single', 'parent.f90', 'child.f90')
test('single-level hierarchy', hier2)
