attempt fixing TestSCons.where_is() for win32

[ptomulik]

When using testing framework for external tests (-e), the method TestSCons.where_is() seems to always return None under win32. This PR fixes this. Tested with one of my projects on appveyor.

[bdbaddog]

Can you point to URL for your appveyor results before/after this change?

[ptomulik]

Can you point to URL for your appveyor results before/after this change?

This job, for example, used the patched testing framework:

https://ci.appveyor.com/project/ptomulik/scons-tool-dvipdfm/builds/20088248/job/i2ke4pfn50uxi481

no skipped tests (means, where_is() detected correctly), while this

https://ci.appveyor.com/project/ptomulik/scons-tool-dvipdfm/builds/20089404/job/4tuf3jdfh6omkv95

uses unpatched testing framework -- three tests skipped (same programs not found by where_is()) .

[ptomulik]

This was the project under test: https://github.com/ptomulik/scons-tool-dvipdfm/tree/0.1.0/

[ptomulik]

From travis-ci (Build system information):

clang version
clang version 7.0.0 (tags/RELEASE_700/final)
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir: /usr/local/clang-7.0.0/bin

looks like they changed default version of clang on Xenial to '7.0.0' . The .travis/install.sh symlinks '5.0.0', but it seems to make clang tests to fail at later stage.

[bdbaddog]

Good catch on clang. was just digging in.
It appears py3.7-dev image only no longer has clang version we're pointing to.. I'll update the travis file

[bdbaddog]

rebase from master?

[ptomulik]

rebase from master?

yes, just did it.

[coveralls]

Coverage decreased (-1.7%) to 79.917% when pulling 210b61f on ptomulik:whereis into 9685d23 on SCons:master.

[coveralls]

Coverage decreased (-1.7%) to 79.917% when pulling 210b61f on ptomulik:whereis into 9685d23 on SCons:master.

[coveralls]

Coverage decreased (-1.7%) to 79.917% when pulling 210b61f on ptomulik:whereis into 9685d23 on SCons:master.

[bdbaddog]

Clear Ci. Merging

[ptomulik]

Thanks!