cmSystemTools: Add IsOn(),IsOff() overloads accepting std::string

Source/cmSystemTools.cxx

@@ -392,6 +392,11 @@ bool cmSystemTools::IsOn(const char* val)
   return (onValues.count(v) > 0);
 }
 
+bool cmSystemTools::IsOn(const std::string& val)
+{
+  return cmSystemTools::IsOn(val.c_str());
+}
+
 bool cmSystemTools::IsNOTFOUND(const char* val)
 {
   if (strcmp(val, "NOTFOUND") == 0) {
@@ -428,6 +433,11 @@ bool cmSystemTools::IsOff(const char* val)
   return (offValues.count(v) > 0);
 }
 
+bool cmSystemTools::IsOff(const std::string& val)
+{
+  return cmSystemTools::IsOff(val.c_str());
+}
+
 void cmSystemTools::ParseWindowsCommandLine(const char* command,
                                             std::vector<std::string>& args)
 {

Source/cmSystemTools.h

@@ -129,6 +129,7 @@ public:
    * as ifdef.
    */
   static bool IsOn(const char* val);
+  static bool IsOn(const std::string& val);
 
   /**
    * does a string indicate a false or off value ? Note that this is
@@ -138,6 +139,7 @@ public:
    * NOTFOUND, *-NOTFOUND or IGNORE will cause IsOff to return true.
    */
   static bool IsOff(const char* val);
+  static bool IsOff(const std::string& val);
 
   ///! Return true if value is NOTFOUND or ends in -NOTFOUND.
   static bool IsNOTFOUND(const char* value);