squash! mingw: HOT FIX: work around environment issues -- again

Add the following clarifier with the next merging rebase:

Note: cURL manages to set the variable CHARSET when nedmalloc is *not*
enabled, without causing an access violation. In that case, it sets it
successfully to the value "cp1252" (hence it is our choice, too, cURL may
need it, Git does not).