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

cmake/Doxyfile.in

@@ -576,7 +576,7 @@ WARN_LOGFILE           =
 # directories like "/usr/src/myproject". Separate the files or directories
 # with spaces.
 
-INPUT                  = @CMAKE_CURRENT_SOURCE_DIR@
+INPUT                  = @FAIL_DOC_SOURCE@
 
 # This tag can be used to specify the character encoding of the source files
 # that doxygen parses. Internally doxygen uses the UTF-8 encoding, which is
@@ -605,7 +605,7 @@ RECURSIVE              = YES
 # excluded from the INPUT source files. This way you can easily exclude a
 # subdirectory from a directory tree whose root is specified with the INPUT tag.
 
-EXCLUDE                = @FAIL_DOC_EXCLUDE@
+EXCLUDE                =
 
 # The EXCLUDE_SYMLINKS tag can be used select whether or not files or
 # directories that are symbolic links (a Unix filesystem feature) are excluded
@@ -619,7 +619,7 @@ EXCLUDE_SYMLINKS       = NO
 # against the file with absolute path, so to exclude all test directories
 # for example use the pattern */test/*
 
-EXCLUDE_PATTERNS       =
+EXCLUDE_PATTERNS       = @FAIL_DOC_EXCLUDE_PATTERNS@
 
 # The EXCLUDE_SYMBOLS tag can be used to specify one or more symbol names
 # (namespaces, classes, functions, etc.) that should be excluded from the