add const to every table in win32/fcrypt.c

See [perl #123386] for details.
make xs_version_bootcheck a static func since not used as export anymore

Since commit db6e00bd00 the function has not been used by XS modules. Now
remove it from export table since it has never been public API (the macro
is), and it saves its symbol name string name, symbol table pointer,
and allows for inlining and/or random calling convention optimization
by the CC.