simplify upstream version checks

[bbolker]

Mikael Jagan has pointed in this thread that checking on built vs. current versions of upstream packages (TMB, Matrix) can be done more easily, without storing the information in an external file (and relying on a customized make rule for the package, by leveraging R's property of storing the environment at build time. A version of this is implemented here for lme4 (it also checks the ABI, rather than the package version, of Matrix). We should back-port this to glmmTMB (and possibly suggest back-porting it to TMB: in particular, TMB could mimic the Matrix ABI-reporting machinery ...)

[jaganmn]

Close-able? #1011