doxygen: doc generation fixed

Doxygen skips undesired directories and files now. In addition, the
documentation of the "fail" namespace has been fixed. Note that there
are still several warnings (due to incomplete documentations) in the
Doxygen output.

Change-Id: Idad4f1ecff453765b307fa40a5c1cebc0c2ce2bb

src/core/sal/SimulatorController.hpp

@@ -11,6 +11,8 @@
 #include "SALConfig.hpp"
 #include "ConcreteCPU.hpp"
 
+
+/// All classes, functions, constants, etc. are encapsulated in the namespace "fail".
 namespace fail {
 
 // Incomplete types suffice here:

src/core/sal/bochs/BochsConfig.hpp

@@ -1,4 +1,5 @@
 /**
+ * \file BochsConfig.hpp
  * \brief Type definitions and configuration settings for
  *        the Bochs simulator.
  */

src/core/sal/gem5/Gem5Config.hpp

@@ -1,4 +1,5 @@
 /**
+ * \file Gem5Config.hpp
  * \brief Type definitions and configuration settings for
  *        the gem5 simulator.
  */

src/core/sal/qemu/QEMUConfig.hpp

@@ -1,4 +1,5 @@
 /**
+ * \file QEMUConfig.hpp
  * \brief Type definitions and configuration settings for the
  * qemu-system-x86_64 target backend.
  */

src/core/sal/t32/T32Config.hpp

@@ -1,4 +1,5 @@
 /**
+ * \file T32Config.hpp
  * \brief Type definitions and configuration settings for the
  *        T32 target backend.
  */