Don't link libtnccs to checksum_builder.

Linking is only required for libraries defining global symbols used by
plugins to which the plugins do not link themselves.

src/checksum/checksum_builder.c

@@ -23,10 +23,6 @@
 #include <daemon.h>
 #include <utils/enumerator.h>
 
-#ifdef HAS_TNC
-#include <tnc/tnc.h>
-#endif
-
 /* we need to fake the pluto symbol to dlopen() the xauth plugin */
 void *pluto;
 
@@ -133,15 +129,11 @@ int main(int argc, char* argv[])
 {
 	int i;
 
-	/* forces link against libhydra/libcharon */
+	/* forces link against libhydra/libcharon, imports symbols needed to
+	 * dlopen plugins */
 	hydra = NULL;
 	charon = NULL;
 
-#ifdef HAS_TNC
-	/* forces link against libtnccs */
-	tnc = NULL;
-#endif
-
 	/* avoid confusing leak reports in build process */
 	setenv("LEAK_DETECTIVE_DISABLE", "1", 0);
 	/* don't use a strongswan.conf, forces integrity check to disabled */