Glob: issue warnings on Directory errors

This will make cmake produce error when recursive globbing fails. For example:

project(foo)
file(GLOB_RECURSE foo /foo/*)

produces

CMake Error at CMakeLists.txt:2 (file):
  Error has occurred while globbing for '/foo/*' - Error listing directory
  '/foo/'! Reason: 'No such file or directory'

To make this into a warning, another change will need to be applied to cmake:

diff --git a/Source/cmFileCommand.cxx b/Source/cmFileCommand.cxx
index f3d49c36a6..428e842f0f 100644
--- a/Source/cmFileCommand.cxx
+++ b/Source/cmFileCommand.cxx
@@ -770,12 +770,17 @@ bool HandleGlobImpl(std::vector<std::string> const& args, bool recurse,
               MessageType::AUTHOR_WARNING,
               "Cyclic recursion detected while globbing for '" + *i + "':\n" +
                 globMessage.content);
-          } else {
+          } else if (globMessage.type == cmsys::Glob::error) {
             status.GetMakefile().IssueMessage(
               MessageType::FATAL_ERROR,
               "Error has occurred while globbing for '" + *i + "' - " +
                 globMessage.content);
             shouldExit = true;
+          } else {
+            status.GetMakefile().IssueMessage(
+              MessageType::LOG,
+              "Error while globbing for '" + *i + "':\n" +
+                globMessage.content);
           }
         }
         if (shouldExit) {

Topic-rename: Directory-error-handling