Set SIO_LOOPBACK_FAST_PATH while creating socket in windows

[karthiknadig]

Fixes #912, #949

@int19h is the try/catch the right way to do this? Do we need to create a new socket in place of pass?

[int19h]

I think it should be safe to proceed with the socket - it oughtn't be invalidated by a failed ioctl.

Also, you might as well just catch AttributeError instead of doing hasattr!

[codecov-io]

Codecov Report

Merging #913 into master will decrease coverage by 0.12%.
The diff coverage is 25%.

@@            Coverage Diff             @@
##           master     #913      +/-   ##
==========================================
- Coverage   55.51%   55.38%   -0.13%     
==========================================
  Files          33       33              
  Lines        4395     4407      +12     
==========================================
+ Hits         2440     2441       +1     
- Misses       1955     1966      +11

Impacted Files	Coverage Δ
ptvsd/socket.py	59.13% <25%> (-3.51%)	⬇️

---

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 182683b...c674803. Read the comment docs.