requesting updates to package.py for CRTM

[BenjaminTJohnson]

@climbfuji

https://github.com/NOAA-EMC/spack/blob/8a949c880aac1781852eb8c1ef45f32668edcdfb/var/spack/repos/builtin/packages/crtm/package.py

Here are the relevant tags for CRTM (https://github.com/JCSDA/crtm):
For JEDI use:
v2.4_jedi ( tag newly created, points to release/crtm_jedi_v2.4.0)
v2.3_jedi.4 ( points to release/crtm_jedi last digit incremented with updates to the release branch)

For EMC use:
v2.4.0_emc ( tag newly created, points to release/REL-2.4.0_emc )
v2.3.0_emc ( tag newly created, points to release/REL-2.3.0_emc )

EMC releases use git-lfs for the binary fix/ directory, but an alternative exists for systems with no git-lfs support.

jedi releases rely on ctest to download fix/ coefficients from GDEX. This download should probably occur during the build process, rather than the ctest.

This is all that spack-stack needs to support right now. The "non-EMC" and "non-jedi" releases of CRTM do not need to be in spack stack.

[climbfuji]

Thanks, @BenjaminTJohnson - I'll work on this in the afternoon.