Make sage -sync-build smarter.

[craigcitro]

As it stands, sage -sync-build simply looks for corresponding C/C++ source files for a given .o or .so file. However, since the vast majority of such files are generated by .pyx files, this means that if you simply delete the .pyx file without deleting the generated C/C++ file, then it won't clean out the compiled object file, which is bad.

We fix this by searching for .pyx files instead. However, there are several C/C++ source files in the sage tree which aren't created from Cython; to keep track of these, we walk through the list of extensions (which is generated by module_list.py and sage/ext/gen_interpreters.py) and make a list of these non-Cython source files, then don't delete things that occur there.

CC: @mwhansen @williamstein

Component: build

Issue created by migration from https://trac.sagemath.org/ticket/6147

[craigcitro]

apply to repo in $SAGE_LOCAL/bin

[craigcitro]

comment:1

Attachment: trac-6147-bin.patch.gz

I'm adding some potential referees to the cc field ...

[mwhansen]

comment:3

Looks good to me.

Merged in 4.0.rc2.