doxygen: make sure the right C source files are included
diff --git a/Doxyfile.vty b/Doxyfile.vty
index 8536e61..91d37a6 100644
--- a/Doxyfile.vty
+++ b/Doxyfile.vty
@@ -610,7 +610,7 @@
# directories like "/usr/src/myproject". Separate the files or directories
# with spaces.
-INPUT = include/osmocom/vty src/vty/*.c
+INPUT = include/osmocom/vty src/vty
# 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