Especially needed for compiling scipy on Windows. On Linux and Mac,
fortran preprocessing is already enabled.

Fixes https://github.com/scipy/scipy/issues/11339

**What does this implement/fix?**

NumPy/SciPy compiled with Intel Fortran compiler using default flags treats both -0.0 and +0.0 as 0.0, however it is not IEEE 754 compliant and some SciPy logic relies on this -0.0 and +0.0 differentiation.

It's very unlikely that `ifort` is supposed to be invoked as `ifort "-fpmodel strict"` instead of `ifort -fpmodel strict` .

Spaces in flag items will end up passed as a single argument.

As numpy is Python 3 only, these import statements are now unnecessary
and don't alter runtime behavior.

After the recent patch to CCompiler.spawn, the file-paths no longer need manual quoting - that's handled as needed within subprocess.

This also states our assumption that our paths do not contain commas.
If we care about this, we could adopt the approach used by https://github.com/rust-lang/rust/issues/38795.

Tested for gcc locally by looking at the error messages of `subprocess.check_call(["gcc", r'-Wl,spaces and no quotes'])`

Other fortran compiler changes not tested, but assumed to be broken in the same way.

Fixes #12882

Note that this was discussed extensively in gh-7287, but removing
this -xhost flag was missed in the PR that closed that issue.

Fixes two problems:

* c compilers do not have a find_executables method.
* get_version return a LooseVersion instance, not string.

Closes #9278.

[ci skip]