Update .gitignore

.gitignore

@@ -1,3 +1,18 @@
+# Ignore files generated by autoconf
+Makefile.in
+aclocal.m4
+auto/
+config.h.in
+configure
+doc/Makefile.in
+m4/libtool.m4
+m4/ltoptions.m4
+m4/ltsugar.m4
+m4/ltversion.m4
+m4/lt~obsolete.m4
+src/Makefile.in
+
+# Ignore files generated by configure
 build/
 .deps/
 /Makefile