Add libc dependency to compiled packages and runtime deps

This commit differentiate linux from other platforms by
using libc compatibility as a criterion for deciding
which buildcaches / binaries can be reused. Other
platforms still use OS compatibility.

On linux a libc is injected by all compilers as an implicit
external, and the compatibility criterion is that a libc is
compatible with all other libcs with the same name and a
version that is lesser or equal.

Some concretization unit tests use libc when run on linux.

var/spack/repos/builtin/packages/aocc/package.py

@@ -28,7 +28,6 @@ class Aocc(Package):
     """
 
     _name = "aocc"
-    family = "compiler"
     homepage = "https://www.amd.com/en/developer/aocc.html"
 
     maintainers("amd-toolchain-support")