cmSystemTools: Add VersionCompareEqual helper

Wrap a call to VersionCompare with OP_EQUAL.

Source/cmSystemTools.cxx

@@ -2776,6 +2776,14 @@ bool cmSystemTools::VersionCompare(cmSystemTools::CompareOp op,
   return op == cmSystemTools::OP_EQUAL;
 }
 
+//----------------------------------------------------------------------------
+bool cmSystemTools::VersionCompareEqual(std::string const& lhs,
+                                        std::string const& rhs)
+{
+  return cmSystemTools::VersionCompare(
+    cmSystemTools::OP_EQUAL, lhs.c_str(), rhs.c_str());
+}
+
 //----------------------------------------------------------------------------
 bool cmSystemTools::VersionCompareGreater(std::string const& lhs,
                                           std::string const& rhs)

Source/cmSystemTools.h

@@ -294,6 +294,8 @@ public:
    * Compare versions
    */
   static bool VersionCompare(CompareOp op, const char* lhs, const char* rhs);
+  static bool VersionCompareEqual(std::string const& lhs,
+                                  std::string const& rhs);
   static bool VersionCompareGreater(std::string const& lhs,
                                     std::string const& rhs);