Fail fast if package being checked fails to install

[gadenbuie]

I just ran into an issue where the dev version of the package being checked failed to install. I initially missed the failure because the warning scrolled off the screen. Once package checks complete, they all end up failing and most with the problem:

Package required but not available: '{package_being_checked}'

It'd be helpful to halt early in the process if the package being checked failed to install.

FYI for anyone else in a similar situation: revdep_check(quiet = FALSE) will reveal the installation error.

[gaborcsardi]

This is kind of difficult, because we rely on install.packages() to install all required packages, and install.packages() does not stop if the installation of a dependency failed.