autogen.sh: Only call autoreconf to generate build system files

autoreconf calls libtoolize and other autotools commands as needed
to generate and install build system files, as described in the man
page. The documentation cautions against using aclocal as it may be
removed in the future; it recommends simply calling autoreconf in
place of calling individual commands to remain forwards compatible:

https://www.gnu.org/software/automake/manual/html_node/Future-of-aclocal.html

Signed-off-by: David Ward <david.ward@ll.mit.edu>

autogen.sh

@@ -79,11 +79,5 @@ then
     find . -name 'Makefile.in' -delete
 
 else
-    libtoolize --force --copy
-
-    aclocal --force
-
-    automake --add-missing --copy
-
-    autoreconf --force
+    autoreconf --force --install
 fi