[Rd] Inappropriate "Unix-alike platforms" in txtProgressBar.Rd in R devel

[Suharto Anggono Suharto Anggono]

In current R devel (r76247), "See Also" section of help page on 'txtProgressBar' (https://svn.r-project.org/R/trunk/src/library/utils/man/txtProgressBar.Rd) has "Unix-alike platforms" as a detail on 'tkProgressBar':
\seealso{
  \code{\link{winProgressBar}} (Windows only),
  \code{\link{tkProgressBar}} (Unix-alike platforms).
}

In fact, 'tkProgressBar' also exists in R on Windows.