Fix compilation

Missing include

Change-Id: If85675529f034ba7bfd329da06e7c01d8ae08912
Reviewed-by: Nikolai Kosjar <nikolai.kosjar@digia.com>

src/plugins/todo/cpptodoitemsscanner.cpp

@@ -33,6 +33,8 @@
 #include <projectexplorer/project.h>
 #include <cplusplus/TranslationUnit.h>
 
+#include <cctype>
+
 namespace Todo {
 namespace Internal {