equix: avoid a coverity warning in hashx_alloc()

This addresses one of the warnings in issue #40792. As far as I can tell
this is a false positive, since the use of "ctx->type" in hashx_free()
can only be hit after the unioned code/program pointer is non-NULL. It's
no big deal to zero this value explicitly to silence the warning though.

Signed-off-by: Micah Elizabeth Scott <beth@torproject.org>

src/ext/equix/hashx/src/context.c

@@ -41,6 +41,7 @@ hashx_ctx* hashx_alloc(hashx_type type) {
 		goto failure;
 	}
 	ctx->code = NULL;
+	ctx->type = 0;
 	if (type & HASHX_COMPILED) {
 		if (!hashx_compiler_init(ctx)) {
 			goto failure;