Do not mark directories as `executable', we only want program files

Patch by Markus Oberhumer.

llvm-svn: 21377

llvm/lib/System/Unix/Path.inc

@@ -311,6 +311,10 @@ Path::writable() const {
 
 bool
 Path::executable() const {
+  struct stat st;
+  int r = stat(path.c_str(), &st);
+  if (r != 0 || !S_ISREG(st.st_mode))
+    return false;
   return 0 == access(path.c_str(), R_OK | X_OK );
 }