For VS10: Really use full path file names.

I naively assumed in my previous commit that the Convert call
would correctly convert a relative path file name correctly
relative to the makefile's current output directory. It actually
converts it relative to the process's current working directory.
So it would be different depending on how you launched cmake-gui.
This commit ensures that the generated files are always the same
by starting with a full path to begin with, based on the makefile
GetCurrentOutputDirectory method.

Source/cmLocalVisualStudio7Generator.cxx

@@ -234,7 +234,9 @@ void cmLocalVisualStudio7Generator
 //----------------------------------------------------------------------------
 cmSourceFile* cmLocalVisualStudio7Generator::CreateVCProjBuildRule()
 {
-  std::string stampName = cmake::GetCMakeFilesDirectoryPostSlash();
+  std::string stampName = this->Makefile->GetCurrentOutputDirectory();
+  stampName += "/";
+  stampName += cmake::GetCMakeFilesDirectoryPostSlash();
   stampName += "generate.stamp";
   const char* dsprule =
     this->Makefile->GetRequiredDefinition("CMAKE_COMMAND");