CI: default flags for win 8.1 x86

8 jobs for ci_windows_new in 70 minutes and 21 seconds (queued for 3 seconds)
Status Job ID Name Coverage
  Prepare
passed #5572
windows10
windows-10-prepare

00:01:34

passed #5573
windows8
windows-8-prepare

00:01:44

 
  Build
passed #5574
windows10
windows-10-build

00:41:36

passed #5587
windows8
windows-8-build

00:27:01

failed #5575
windows8
windows-8-build

00:36:21

 
  External
passed cdash:windows-10-x64-vc14.0

passed cdash:windows-8.1-x86-vc14.0

passed cdash:windows-8.1-x86-vc14.0