Some easyblocks hardwired to leverage `CPATH` but this may not be available under some configurations

[ocaisa]

With recent EB releases, a configuration like

EASYBUILD_MODULE_SEARCH_PATH_HEADERS=include_paths
EASYBUILD_SEARCH_PATH_CPP_HEADERS=include_paths

means there is now a scenario where CPATH is never (or at least almost never) set. However there seem to be a few easyblocks that are still hard-coded to use/access CPATH:

• easybuild-easyblocks/easybuild/easyblocks/q/qt.py

  Line 102 in 2a7aad7

  'CFLAGS': 'QMAKE_CFLAGS',

• easybuild-easyblocks/easybuild/easyblocks/r/root.py

  Line 67 in 2a7aad7

  cpath = os.getenv('CPATH')

• easybuild-easyblocks/easybuild/easyblocks/x/xmipp.py

  Line 230 in 2a7aad7

  env.setvar('CPATH', os.pathsep.join([os.environ['CPATH'], pyincpath]))

• easybuild-easyblocks/easybuild/easyblocks/r/rosetta.py

  Line 128 in 2a7aad7

  cpaths = os.getenv('CPATH')

• easybuild-easyblocks/easybuild/easyblocks/c/cuda.py

  Line 111 in 2a7aad7

  self.module_load_environment.CPATH = inc_path

• easybuild-easyblocks/easybuild/easyblocks/t/tbb.py

  Line 232 in 2a7aad7

  txt += self.module_generator.prepend_paths('CPATH', [os.path.join(self.tbb_subdir, 'include')])

• easybuild-easyblocks/easybuild/easyblocks/c/clang_aomp.py

  Line 229 in 2a7aad7

  component['prebuildopts'] = "unset CPATH && "

• easybuild-easyblocks/easybuild/easyblocks/n/numpy.py

  Line 464 in 2a7aad7

  txt += self.module_generator.prepend_paths('CPATH', os.path.join(numpy_core_dir, 'include'))

• easybuild-easyblocks/easybuild/easyblocks/p/petsc.py

  Line 97 in 2a7aad7

  self.module_load_environment.CPATH = self.inc_dirs

• easybuild-easyblocks/easybuild/easyblocks/generic/cmakemake.py

  Line 84 in 2a7aad7

  cpaths = os.getenv('CPATH', '').split(os.pathsep)

• easybuild-easyblocks/easybuild/easyblocks/t/tensorflow_compression.py

  Line 99 in 2a7aad7

  action_env['CPATH'] = INHERIT

• easybuild-easyblocks/easybuild/easyblocks/o/opencv.py

  Line 262 in 2a7aad7

  txt += self.module_generator.prepend_paths('CPATH', os.path.join('include', 'opencv4'))

• easybuild-easyblocks/easybuild/easyblocks/l/libxml2.py

  Line 139 in 2a7aad7

  txt += self.module_generator.prepend_paths('CPATH', [os.path.join('include', 'libxml2')])

[ocaisa]

I'm not certain that is an exhaustive list