Fixes issue 46 with clang and msvc

[matbech]

Fixes issue #46

[eldiener]

If you close this PR and reopen it the tests should now run correctly. But I need some clang on Windows command line and some simple test code which shows the bug you are trying to fix. If I run the mpl tests with clang on Windows 10.0, all tests currently pass without errors. If you see errors in the clang on Windows tests, please post your toolset definition for clang on Windows.

[codecov]

Codecov Report

Merging #49 (d8f8e2e) into develop (3301d91) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff            @@
##           develop      #49   +/-   ##
========================================
  Coverage    94.73%   94.73%           
========================================
  Files            5        5           
  Lines           19       19           
========================================
  Hits            18       18           
  Misses           1        1           

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 3301d91...d8f8e2e. Read the comment docs.