add_custom_target: Add output checks for custom target byproducts

Use the output checks for byproducts of add_custom_command also for byproducts
of add_custom_target.

Source/cmAddCustomTargetCommand.cxx

@@ -4,6 +4,7 @@
 
 #include <utility>
 
+#include "cmCheckCustomOutputs.h"
 #include "cmCustomCommandLines.h"
 #include "cmExecutionStatus.h"
 #include "cmGeneratorExpression.h"
@@ -205,6 +206,11 @@ bool cmAddCustomTargetCommand(std::vector<std::string> const& args,
     return false;
   }
 
+  // Make sure the byproduct names and locations are safe.
+  if (!cmCheckCustomOutputs(byproducts, "BYPRODUCTS", status)) {
+    return false;
+  }
+
   // Add the utility target to the makefile.
   bool escapeOldStyle = !verbatim;
   cmTarget* target = mf.AddUtilityCommand(