[Dependencies] Do not check for Xcode 9.4 on Catalina. (#6605)

system-dependencies.sh

@@ -521,7 +521,11 @@ function check_xcode () {
 	# must have latest Xcode in /Applications/Xcode<version>.app
 	check_specific_xcode
 	install_coresimulator
-	check_specific_xcode "94"
+	# Xcode 9,4 does not longer start on catalina
+	local current_os=$(sw_vers -productVersion)
+	if test $current_os != "10.15"; then
+		check_specific_xcode "94"
+	fi
 
 	local XCODE_DEVELOPER_ROOT=`grep ^XCODE_DEVELOPER_ROOT= Make.config | sed 's/.*=//'`
 	local IOS_SDK_VERSION=`grep ^IOS_SDK_VERSION= Make.config | sed 's/.*=//'`