Improve autogen.sh.

diff --git a/Makefile.am b/Makefile.am
index cd90b6c..52f2caf 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -2,6 +2,8 @@
 
 ACLOCAL_AMFLAGS = -I m4
 
+AUTOMAKE_OPTIONS = foreign
+
 SUBDIRS = src
 
 EXTRA_DIST =                                                                 \