Add several workarounds for WSL (Windows Subsystem for Linux)

See microsoft/WSL#352 and microsoft/WSL#1887 for details.

runcoms/zprofile

@@ -69,3 +69,23 @@ export LESS='-F -g -i -M -R -S -w -X -z-4'
 if (( $#commands[(i)lesspipe(|.sh)] )); then
   export LESSOPEN="| /usr/bin/env $commands[(i)lesspipe(|.sh)] %s 2>&-"
 fi
+
+#
+# WSL (Windows Subsystem for Linux)
+#
+
+if [[ -f /proc/version ]] && grep -q "Microsoft" /proc/version; then
+  # Force tmux use /bin/zsh as the default shell instead of /bin/bash.
+  export SHELL="/bin/zsh"
+
+  # Enable access to VcXSrv/Xming.
+  export DISPLAY=":0.0"
+
+  # Fix umask value if WSL didn't set it properly.
+  # https://github.com/Microsoft/WSL/issues/352
+  [[ "$(umask)" == "000" ]] && umask 022
+
+  # Don't change priority of background processes with nice.
+  # https://github.com/Microsoft/WSL/issues/1887
+  unsetopt BG_NICE
+fi