make install should install .v files and .glob files in addition to .vo files

[JasonGross]

If compcert does not install .v and .glob files, the bug minimizer cannot minimize any bugs in projects that are built on top of compcert.

Note that coq_makefile-made makefiles install the .v and .glob files:
https://github.com/coq/coq/blob/5eedc0b094c7aff4b10e89c547dcb79e1cc672c3/tools/CoqMakefile.in#L396-L401

[JasonGross]

I have created #527 for the .v file part. I am not sure how to install the .glob files, as it seems they are not even fully generated by the makefile (different directories overwrite each others' .glob files it seems). Why does compcert invoke -dump-glob explicitly rather than allowing coq to dump the glob file alongside the .v files? This code dates back to the initial git import of compcert.