clang-x86-ninja-win10 - replacing backslashes

in buildbot.tac with forward slashes to address re-configuration
cycles in cmake
diff --git a/buildbot/google/docker/buildbot-windows10-vs2019/VERSION b/buildbot/google/docker/buildbot-windows10-vs2019/VERSION
index 60d3b2f..b6a7d89 100644
--- a/buildbot/google/docker/buildbot-windows10-vs2019/VERSION
+++ b/buildbot/google/docker/buildbot-windows10-vs2019/VERSION
@@ -1 +1 @@
-15
+16
diff --git a/buildbot/google/docker/buildbot-windows10-vs2019/run.ps1 b/buildbot/google/docker/buildbot-windows10-vs2019/run.ps1
index 67d1b05..0030146 100644
--- a/buildbot/google/docker/buildbot-windows10-vs2019/run.ps1
+++ b/buildbot/google/docker/buildbot-windows10-vs2019/run.ps1
@@ -35,6 +35,12 @@
 # Note: Powershell does NOT exit on non-zero return codes, so we need to check manually.
 if ($LASTEXITCODE -ne 0) { throw "Exit code is $LASTEXITCODE" }
 
+# Replace backward slashes with forward slashes on buildbot.tac
+# Otherwise Cmake will go into infinite re-configuration loops
+$buildbottac=Get-Content -Path "buildbot.tac"
+$buildbottac=$buildbottac -replace "\\\\", "/"
+$buildbottac | Set-Content -Path "buildbot.tac"
+
 # start the daemon, as this does not print and logs to std out, run it in the background
 Write-Output "starting worker..."
 cmd /c Start /B buildslave start Q:
diff --git a/buildbot/google/terraform/main.tf b/buildbot/google/terraform/main.tf
index 2efe7af..6c946d7 100644
--- a/buildbot/google/terraform/main.tf
+++ b/buildbot/google/terraform/main.tf
@@ -205,7 +205,7 @@
 
       spec {
         container {
-          image = "${var.gcp_config.gcr_prefix}/buildbot-windows10-vs2019:15"
+          image = "${var.gcp_config.gcr_prefix}/buildbot-windows10-vs2019:16"
           name  = "windows10-vs2019"
 
           # reserve "<number of cores>-1" for this image, kubernetes also