Fix generate_trig_table build target.

It now closely resembles the js2c target, so that we only have
one platform to run it on (either 'host' or 'target'). This way
we do not run into warnings when compiling for e.g. ARM.

R=jkummerow@chromium.org

Review URL: https://codereview.chromium.org/85893002

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@18067 ce2b1a6d-e550-0410-aec6-3dcde31c8c00