sysutils/polkit: repair build with option SPIDERMONKEY

As described in the PR, the dependency listed in the ports
Makefile was spidermonkey 102, but the software itself was
looking for spidermonkey 115. Since 115 is now in ports,
we can chase it. No PORTREVISION because this is just a build
fix (for non-default arguments, at that).

PR 280291