Revert "add fast-fail feature for pending builds in PR's"

This reverts commit 8008ab6a.

appveyor.yml

@@ -26,10 +26,6 @@ cache:
 - x86_64-4.9.2-release-win32-seh-rt_v3-rev1.7z
 build_script:
 - ps: |
-    if ($env:APPVEYOR_PULL_REQUEST_NUMBER -and $env:APPVEYOR_BUILD_NUMBER -ne ((Invoke-RestMethod `
-      https://ci.appveyor.com/api/projects/$env:APPVEYOR_ACCOUNT_NAME/$env:APPVEYOR_PROJECT_SLUG/history?recordsNumber=50).builds | `
-      Where-Object pullRequestId -eq $env:APPVEYOR_PULL_REQUEST_NUMBER)[0].buildNumber) { `
-      throw "There are newer queued builds for this pull request, failing early." }
     mkdir build
     cd build
     if ($env:GENERATOR -ne "MSYS Makefiles") {