add IDEWorkspaceChecks.plist to source control

Per the Xcode release notes: 'Xcode 9.3 adds a new IDEWorkspaceChecks.plist file to a workspace's shared data, to store the state of necessary workspace checks. Committing this file to source control will prevent unnecessary rerunning of those checks for each user opening the workspace. (37293167'

https://developer.apple.com/library/content/releasenotes/DeveloperTools/RN-Xcode/Chapters/Introduction.html

Author: beOn

Builds/MacOSX/OpenEphys.xcworkspace/xcshareddata/IDEWorkspaceChecks.plist

@@ -0,0 +1,8 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
+<plist version="1.0">
+<dict>
+	<key>IDEDidComputeMac32BitWarning</key>
+	<true/>
+</dict>
+</plist>