[clang] [MinGW] Link kernel32 once after the last instance of msvcrt

The msvcrt library isn't a pure import library; it does contain
regular object files with wrappers/fallbacks, and these can require
linking against kernel32.

This only makes a difference when linking with ld.bfd, as lld
always searches all static libraries.

This matches a similar change made recently in gcc in
https://gcc.gnu.org/git/?p=gcc.git;a=commitdiff;h=850533ab160ef40eccfd039e1e3b138cf26e76b8,
although clang adds --start-group --end-group around these libraries
if -static is specified, which gcc doesn't. But try to match gcc's
linking order in any case, for consistency.

Differential Revision: https://reviews.llvm.org/D80880