[autobuild] autogen.sh remove generated files before creating new ones

configure complained that "missing" didn't support something;
it seems autotools fail to update the generated scripts

also cleanup .gitignore

.gitignore

@@ -1,19 +1,14 @@
-.lock-wscript*
-.waf-*/
 *build/
-ragel.pyc
 Makefile.in
-Makefile
-m4
 aclocal.m4
+ar-lib
 autom4te.cache
-compile
 config.guess
 config.sub
 configure
 depcomp
 install-sh
 ltmain.sh
+m4
 missing
-mkinstalldirs
 include/lighttpd/config.h.in

autogen.sh

@@ -17,12 +17,19 @@ ARGV0=$0
 
 set -e
 
+if [ ! -f configure.ac -o ! -f COPYING ]; then
+	echo "Doesn't look like you're in the source directory" >&2
+	exit 1
+fi
 
 run() {
 	echo "$ARGV0: running \`$@'"
 	$@
 }
 
+run rm -f aclocal.m4 ar-lib config.guess config.sub configure depcomp instal-sh ltmain.sh missing
+run rm -rf m4 autom4te.cache
+
 run $LIBTOOLIZE $LIBTOOLIZE_FLAGS
 run $ACLOCAL $ACLOCAL_FLAGS
 run $AUTOHEADER