pp.c: Fixed a quotemeta bug on perls built without locale.

This was causing quotemeta("\N{U+D7}") to not be quoted, as well as
some other codepoints in the latin1 range.
t/re/subst.t: Proper skip for systems without locale
Makefile.SH: Fix cross builds with -Uhostgenerate
Makefile.SH: Add missing files for make test on cross builds