support ASCII locale for ICU

git-svn-id: https://svn.r-project.org/R/trunk@67071 00db46b3-68df-0310-9c12-caf00c1e9a41
report ASCII collation if in use


git-svn-id: https://svn.r-project.org/R/trunk@67072 00db46b3-68df-0310-9c12-caf00c1e9a41
documentation typo


git-svn-id: https://svn.r-project.org/R/trunk@67073 00db46b3-68df-0310-9c12-caf00c1e9a41