Error: "Could not find build tools necessary to build stringi" when trying devtools::install_github()
<p>Trying
    devtools::install_github("Rexamine/stringi")
and getting error:
Could not find build tools necessary to build stringi</p>

<p>I see several people have had this error but the solutions haven't worked for me. I reinstalled xcode because the command line tools seemed to be the problem for other people. Checked the paths for R and RStudio, I can open both fine (from the terminal as well). Don't think this is an Rtools issue but I can't figure out where the problem is. Has anyone had any luck with this particular devtools error?</p>

<p>Running OSX 10.11.6, RStudio Version 0.99.896, R 3.2.1 GUI 1.66 Mavericks build (6956), XCode Version 7.3.1 (7D1014). </p>