Trying to fix linker errors

.appveyor.yml

@@ -7,9 +7,6 @@ os:
 environment:
   CTEST_OUPTUT_ON_FAILURE: ON
 
-configuration:
-  - Debug
-
 branches:
   except:
     - gh-pages

include/CLI/Validators.hpp

@@ -27,7 +27,7 @@ namespace CLI {
 bool ExistingFile(std::string filename) {
     struct stat buffer;   
     bool exist = stat(filename.c_str(), &buffer) == 0; 
-    bool is_dir = (buffer.st_mode & S_IFDIR != 0);
+    bool is_dir = (buffer.st_mode & S_IFDIR) != 0;
     if(!exist) {
         std::cerr << "File does not exist: " << filename << std::endl;
         return false;