Rewrite as URL adding equals sign to end of url.

Problem/Motivation

Currently drupal_get_query_array does't support a syntax like that 'http://domain.org?flag' because it sets the value
of flag to "". If drupal_http_build_query is called on this it is converted to 'http://domain.org?flag=' which is wrong.

Proposed resolution

Let drupal_get_query_array return what's expected.

Remaining tasks

Write tests, write a patch.

Original report by [robit8deb]

// Text of original report here.
(for legacy issues whose initial post was not the issue summary)
I have a scenario where a customer is using an external website in correlation with his drupal site. The external vendor is using poorly formatted urls that are getting (correctly) rewritten with and = sign at the end because it is expecting a value. For example, http:///foo.cgi?foo gets rewritten to http:///foo.cgi?foo=. I need to turn off this validation because the resulting url with the = sign at the end takes the user to page cannot be displayed.

I fixed this behavior on link cck fields using this patch:

http://drupal.org/node/1306352

However, the field that i am rewriting now is a Boolean field where, when on, gets rewritten to a link.

Please advise.