[doxygen] Do not scan the whole source tree

Doxygen is rather verbose and scanning .git subdirectory produces a
lot of noise.

Limit scanning only to to subdirectories that have data for doxygen.

Signed-off-by: Simo Piiroinen <simo.piiroinen@jollamobile.com>

Doxyfile

@@ -542,7 +542,7 @@ WARN_LOGFILE           =
 # directories like "/usr/src/myproject". Separate the files or directories 
 # with spaces.
 
-INPUT                  = 
+INPUT                  = include/mce
 
 # 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