POSIX:strtod() should restore the locale it changed

POSIX:strtod() should restore the locale it changed

Prior to this commit, the locale remained as strtod() set it to.  I
could not find a case where this actually was a problem, as the other
code is good about checking for and changing the locale where needed.
But uses of atoi(), strtol() in locales where there are spaces in
numbers likely would break.