[Rd] Needless updating of HTML package descriptions

[Gabor Grothendieck]

I recently installed a local package which failed because the package
was already loaded; however, then it tried to update all the HTML
package descriptions needlessly (since they had not changed due
to the failure to install).  Since updating the HTML package descriptions
can be time consuming the processing should skip the update in this case.

> utils:::menuInstallLocal()
Warning: package 'myPackage' is in use and will not be installed
updating HTML package descriptions