libselinux: setexecfilecon(): drop dead assignment

The variable `rc` is always unconditionally assigned by the next call of
`setexeccon()` and never read in between.

Found by clang-analyzer.

Signed-off-by: Christian Göttsche <cgzones@googlemail.com>

libselinux/src/setexecfilecon.c

@@ -37,7 +37,6 @@ int setexecfilecon(const char *filename, const char *fallback_type)
 		newcon = strdup(context_str(con));
 		if (!newcon)
 			goto out;
-		rc = 0;
 	}
 
 	rc = setexeccon(newcon);