Revert "Remove unnecessary windows.h include"

This reverts commit e6d1e13b2880ab0e6166e5ed168df7e6e0de943b.

We do need this (for the CLI tools).

Fixes a build failure on MinGW:
  CC       tar/bsdtar-bsdtar.o
In file included from tar/bsdtar_platform.h:62:0,
                 from tar/bsdtar.c:26:
./libarchive/archive_entry.h:250:64: error: unknown type name 'BY_HANDLE_FILE_INFORMATION'
 __LA_DECL void archive_entry_copy_bhfi(struct archive_entry *, BY_HANDLE_FILE_INFORMATION *);
                                                                ^
Better fix.

Restore e6d1e13b2880ab0e6166e5ed168df7e6e0de943b,
and make sure that we include windows.h earlier for the CLI tools.
Fix cpio build on MinGW.

Exact same concept as the previous commit.
Fix previous commit.

Forgot to check if cpio_windows.h actually pulled windows.h in ;p.
More MinGW trickery...

Poor man's attempt at making 4e002d9a92ecd7cec0fb98b0bedbace8aad81f6e
play nice with MinGW.
Dry coded for the fastest solution, there's probably a much better
way to handle that sanely & properly.
Merge branch 'master' into fix-mingw
Harmless typo in a comment.
Move the strsep() implementation to the mtree reader, which is
the only place it's used.