Allow user to select what extensions to compile and install

Signed-off-by: Jan Engelhardt <jengelh@computergmbh.de>

extensions/Makefile.am

@@ -1,36 +0,0 @@
-# -*- Makefile -*-
-
-AUTOMAKE_OPTIONS = foreign subdir-objects
-abssrcdir        = $(shell readlink -f ${srcdir})
-
-regular_CFLAGS  := @regular_CFLAGS@
-xtables_CFLAGS  := @xtables_CFLAGS@
-kinclude_CFLAGS := @kinclude_CFLAGS@
-AM_CFLAGS        = ${regular_CFLAGS} -I ${top_srcdir}/include \
-                   ${xtables_CFLAGS} ${kinclude_CFLAGS} \
-                   -D_INIT=$*_init
-AM_LDFLAGS       = -module -avoid-version
-xtlib_LTLIBRARIES = \
-	libxt_LOGMARK.la \
-	libxt_TARPIT.la \
-	libxt_TEE.la
-
-#
-#	Call out to kbuild
-#
-.PHONY: modules modules_install clean_modules
-
-all-local: modules
-
-install-exec-local: modules_install
-
-clean-local: clean_modules
-
-modules:
-	make -C ${kbuilddir} M=${abssrcdir} modules;
-
-modules_install:
-	make -C ${kbuilddir} M=${abssrcdir} INSTALL_MOD_PATH=${DESTDIR} modules_install;
-
-clean_modules:
-	make -C ${kbuilddir} M=${abssrcdir} clean;