Fixes for the new SDK

The commits which are in sschuberth/git and not in here are (pasted from private mail from @sschuberth):
* 75e415e Makefile: Do not install built-ins
* ffb434c MinGW: Use MakeMaker to build the Perl libraries
* 617433c Documentation: make AsciiDoc links always point to HTML files (*)
* b543717 MSVC: fix stat definition hell (*)
* 296f510 MinGW: Fix stat definitions to work with MinGW runtime version 4.0 (*)
* 72631c9 mailmap: work around implementations with pure inline strcasecmp (*)
* ab94cf6 Windows: do not redefine _WIN32_WINNT (*)
* d892bec t0061: Work around a line endings issue with newer versions of
cat on MSYS
* adfa3c9 Makefile: Set htmldir to match the default HTML docs location under MSYS
* 159ea1a t7800: Use "test_cmp_text" in all places where "echo" is used

The starred ones (*) are supposedly already upstream.
I picked the necessary ones here.

The omission of 75e415e is on purpose as that feature is not ready yet.