Introduce TKM specific charon daemon (charon-tkm)

Analogous to charon-nm the charon-tkm daemon is a specialized charon
instance used in combination with the trusted key manager (TKM) written
in Ada.

The charon-tkm is basically a copy of the charon-nm code which will
register it's own TKM specific plugins.

The daemon binary is built using the gprbuild utility. This is needed
because it uses the tkm-rpc Ada library and consequently the Ada
runtime. gprbuild takes care of the complete binding and linker steps
required to properly initialize the Ada runtime.

src/charon-tkm/Makefile.am

@@ -0,0 +1,63 @@
+SRC = $(top_builddir)/src
+
+# includes relative to obj directory
+INCLUDES = \
+	-include $(top_builddir)/config.h \
+	-I../$(SRC)/libstrongswan \
+	-I../$(SRC)/libhydra \
+	-I../$(SRC)/libcharon
+
+LIBLD = \
+	-L$(SRC)/libstrongswan/.libs \
+	-L$(SRC)/libhydra/.libs \
+	-L$(SRC)/libcharon/.libs
+LIBPT = $(SRC)/libstrongswan/.libs:$(SRC)/libhydra/.libs:$(SRC)/libcharon/.libs
+LIBFL = -lstrongswan -lhydra -lcharon
+
+DEFS += -DPLUGINS=\""$(PLUGINS)\"" -DIPSEC_PIDDIR=\"${piddir}\"
+
+BUILD_OPTS = \
+	-cargs $(INCLUDES) $(DEFS) \
+	-largs $(LIBLD) $(LIBFL)
+
+# plugins to enable
+PLUGINS = \
+	aes \
+	constraints \
+	gmp \
+	hmac \
+	kernel-netlink \
+	nonce \
+	pem \
+	pkcs1 \
+	pkcs8 \
+	random \
+	sha1 \
+	sha2 \
+	stroke \
+	socket-default \
+	x509
+
+all: build_charon
+
+build_charon: build_charon.gpr src/charon-tkm.c
+	@$(GPRBUILD) -p $< $(BUILD_OPTS)
+
+build_tests: build_tests.gpr
+	@$(GPRBUILD) -p $< $(BUILD_OPTS) -cargs @CHECK_CFLAGS@ -largs @CHECK_LIBS@
+
+if UNITTESTS
+check: build_tests
+	@LD_LIBRARY_PATH=$(LIBPT) obj/test_runner
+else
+check:
+	@echo "reconfigure with --enable-unit-tests"
+endif
+
+install: build_charon
+	$(INSTALL) -m 755 obj/charon-tkm $(DESTDIR)$(ipsecdir)
+
+clean:
+	rm -rf obj
+
+EXTRA_DIST = build_charon.gpr build_common.gpr build_tests.gpr src tests