suggested fix for maacheck (closes #685)

[eddelbuettel]

No description provided.

[codecov-io]

Codecov Report

Merging #686 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #686   +/-   ##
=======================================
  Coverage   89.77%   89.77%           
=======================================
  Files          66       66           
  Lines        3511     3511           
=======================================
  Hits         3152     3152           
  Misses        359      359

Impacted Files	Coverage Δ
inst/include/Rcpp/exceptions.h	50% <ø> (ø)	⬆️

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[eddelbuettel]

@kevinushey @nathan-russell @thirdwing @jjallaire -- any comments?

It's the last Rf_mkString and Rf_install interaction remaining.

[eddelbuettel]

Re-pinging @kevinushey @nathan-russell @thirdwing @jjallaire just in case but will commit unless anybody screams. This should be harmless.

[eddelbuettel]

Thank you both!