ssl_test_lib.[hc]: new source file for common SSL test code

Create a new source file for code that is shared between ssl_client2.c
and ssl_server2.c. This commit only creates the file; subsequent
commits will populate it.

Add it to the official build systems (make, cmake, VS).

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
diff --git a/programs/Makefile b/programs/Makefile
index f53724e..8bb7f2b 100644
--- a/programs/Makefile
+++ b/programs/Makefile
@@ -267,9 +267,13 @@
 	echo "  CC    ssl/ssl_client1.c"
 	$(CC) $(LOCAL_CFLAGS) $(CFLAGS) ssl/ssl_client1.c  $(LOCAL_LDFLAGS) $(LDFLAGS) -o $@
 
-SSL_TEST_OBJECTS = test/query_config.o
+SSL_TEST_OBJECTS = test/query_config.o ssl/ssl_test_lib.o
 
-ssl/ssl_client2$(EXEXT): ssl/ssl_client2.c $(SSL_TEST_OBJECTS) $(DEP)
+ssl/ssl_test_lib.o: ssl/ssl_test_lib.c ssl/ssl_test_lib.h $(DEP)
+	echo "  CC    ssl/ssl_test_lib.c"
+	$(CC) $(LOCAL_CFLAGS) $(CFLAGS) -c ssl/ssl_test_lib.c -o $@
+
+ssl/ssl_client2$(EXEXT): ssl/ssl_client2.c $(SSL_TEST_OBJECTS) ssl/ssl_test_lib.h $(DEP)
 	echo "  CC    ssl/ssl_client2.c"
 	$(CC) $(LOCAL_CFLAGS) $(CFLAGS) ssl/ssl_client2.c $(SSL_TEST_OBJECTS) $(LOCAL_LDFLAGS) $(LDFLAGS) -o $@