Do not ship autogen.sh in the tarball

Copied from libabc.
diff --git a/Makefile.am b/Makefile.am
index eb35adf..279f3a0 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -1,4 +1,5 @@
-EXTRA_DIST = autogen.sh
+EXTRA_DIST =
+CLEANFILES =
 ACLOCAL_AMFLAGS = -I m4 ${ACLOCAL_FLAGS}
 AM_MAKEFLAGS = --no-print-directory
 
@@ -17,8 +18,6 @@
 	-Wl,--gc-sections \
 	-Wl,--as-needed
 
-CLEANFILES =
-
 LIBKMOD_CURRENT=0
 LIBKMOD_REVISION=0
 LIBKMOD_AGE=0