libselinux: context_new(): drop dead assignment

The variable `i` is not used inside this loop, and it later
unconditionally set to 0.

Found by clang-analyzer.

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

libselinux/src/context.c

@@ -37,7 +37,7 @@ context_t context_new(const char *str)
 	}
 	n->current_str = n->component[0] = n->component[1] = n->component[2] =
 	    n->component[3] = 0;
-	for (i = count = 0, p = str; *p; p++) {
+	for (count = 0, p = str; *p; p++) {
 		switch (*p) {
 		case ':':
 			count++;