use lower case and not short path for uniq paths on window

Source/cmNMakeMakefileGenerator.cxx

@@ -711,3 +711,9 @@ std::string cmNMakeMakefileGenerator::CreateMakeVariable(const char* s, const ch
   cmSystemTools::ReplaceString(ret, "-", "_");
   return ret;
 }
+
+std::string cmNMakeMakefileGenerator::LowerCasePath(const char* path)
+{
+  return cmSystemTools::LowerCase(path);
+}
+

Source/cmNMakeMakefileGenerator.h

@@ -90,7 +90,7 @@ protected:
   virtual std::string ConvertToOutputPath(const char* s);
 
   virtual std::string CreateMakeVariable(const char* s, const char* s2);
-
+  virtual std::string LowerCasePath(const char* path);
 private:
   std::string m_LibraryPathOption;// option to specifiy a link path -LIBPATH 
   std::string m_LibraryLinkOption; // option to specify a library (like -l, empty for nmake)

Source/cmUnixMakefileGenerator.cxx

@@ -1356,7 +1356,7 @@ bool cmUnixMakefileGenerator::OutputObjectDepends(std::ostream& fout)
 // by the class cmMakeDepend GenerateMakefile
 void cmUnixMakefileGenerator::OutputCheckDepends(std::ostream& fout)
 {
-  std::set<std::string> emittedShortPath;
+  std::set<std::string> emittedLowerPath;
   std::set<std::string> emitted;
   // Iterate over every target.
   std::map<cmStdString, cmTarget>& targets = m_Makefile->GetTargets();
@@ -1388,13 +1388,9 @@ void cmUnixMakefileGenerator::OutputCheckDepends(std::ostream& fout)
             {
             std::string dependfile = 
               this->ConvertToOutputPath(cmSystemTools::CollapseFullPath(dep->c_str()).c_str());
-            // use the short path function to create uniqe names
-            std::string shortpath;
-            if(!cmSystemTools::GetShortPath(dependfile.c_str(), shortpath))
-              {
-              shortpath = dependfile;
-              }
-            if(emittedShortPath.insert(shortpath).second)
+            // use the lower path function to create uniqe names
+            std::string lowerpath = this->LowerCasePath(dependfile.c_str());
+            if(emittedLowerPath.insert(lowerpath).second)
               {
               emitted.insert(dependfile);
               fout << " \\\n" << dependfile ;

Source/cmUnixMakefileGenerator.h

@@ -169,6 +169,13 @@ protected:
       return std::string(s) + std::string(s2);
     }
   
+  ///! if the OS is case insensitive then return a lower case of the path.
+  virtual std::string LowerCasePath(const char* path)
+    {
+      return std::string(path);
+    }
+  
+  
 protected:
   std::string m_ExecutableOutputPath;
   std::string m_LibraryOutputPath;