appveyor: Add build configuration for AppVeyor CI

This commit adds a build configuration for https://www.appveyor.com/


to test mingw32-based Windows builds.

Additionally it includes a post-build step to package the resulting
Win32 binaries and provide them (for download) as AppVeyor artifacts.
Signed-off-by: Bernhard Nortmann <bernhard.nortmann@web.de>

.appveyor/install-libusb.cmd

+REM This is a batch file to help with setting up the libusb dependency.
+REM It is intended to be run as "install" step from within AppVeyor.
+
+REM desired version and download URL
+set VER=libusb-1.0.20
+set URL=https://sourceforge.net/projects/libusb/files/libusb-1.0/%VER%/%VER%.7z/download
+
+mkdir libusb
+cd libusb
+curl -fLsS -o %VER%.7z %URL%
+7z x %VER%.7z
+cd ..

.appveyor/package-artifacts.cmd

+REM Create an archive from the built binaries and required libraries (DLLs).
+REM For users' convenience, we also include the libusb "listdevs.exe" and our
+REM markdown documentation/license.
+REM AppVeyor will run this as "after_build" step.
+
+mkdir dist
+set FILES=*.exe *.md
+set FILES=%FILES% .\libusb\MinGW32\dll\*.dll
+set FILES=%FILES% .\libusb\examples\bin32\listdevs.exe
+7z a dist\sunxi-tools-win32.7z %FILES%

appveyor.yml

+# Build configuration file for AppVeyor, https://www.appveyor.com/
+version: 'v1.4 #{build}'
+
+shallow_clone: true
+os: MinGW
+
+environment:
+  CC: gcc
+  CFLAGS: -g -O2
+
+install:
+  - cmd: .appveyor/install-libusb.cmd
+
+# Build via Makefile
+build_script:
+  - cmd: set PATH=C:\MinGW\bin;%PATH%
+  - cmd: mingw32-make LIBUSB_CFLAGS="-I libusb/include/libusb-1.0" LIBUSB_LIBS="-L libusb/MinGW32/dll -lusb-1.0"
+  - cmd: mingw32-make misc
+
+after_build:
+  - cmd: .appveyor/package-artifacts.cmd
+
+artifacts:
+  - path: dist\sunxi-tools-win32.7z
+    name: sunxi-tools-win32