EVIS: Add policy CMP0053

This policy switches between the old EVIS parser and the new, faster
parser.

Source/cmPolicies.cxx

@@ -354,6 +354,11 @@ cmPolicies::cmPolicies()
     "Reject source and build dirs in installed "
     "INTERFACE_INCLUDE_DIRECTORIES.",
     3,1,0, cmPolicies::WARN);
+
+  this->DefinePolicy(
+    CMP0053, "CMP0053",
+    "Simplify variable reference and escape sequence evaluation.",
+    3,1,0, cmPolicies::WARN);
 }
 
 cmPolicies::~cmPolicies()

Source/cmPolicies.h

@@ -108,6 +108,8 @@ public:
     CMP0052, ///< Reject source and build dirs in installed
     /// INTERFACE_INCLUDE_DIRECTORIES
 
+    CMP0053, ///< Simplify variable reference and escape sequence evaluation
+
     /** \brief Always the last entry.
      *
      * Useful mostly to avoid adding a comma the last policy when adding a new