commit msys_build.sh for reusing dependencies from nightlies

(cherry picked from commit a716faf52f175ae7f5b5a277af0bbc9530481c27)

add linux-to-windows cross compile to msys_build.sh

be more careful about ARCH vs XC_HOST

use windows version of 7z with wine for cross-compile

use pcre_h.jl from binary instead of downloading pcre rpm

use a switch case, remove appveyor specific code

(cherry picked from commit b3b84568c0936162178eed473b62c9d22e80e0bc)
Create appveyor.yml

(cherry picked from commit fae354ea0a8977654906987502e3b3e8843d6873)

Don't run appveyor on personal branches for now

they should still build when there is a PR opened for them
(cherry picked from commit 9322ca44b791a05657f9d1eef852ee1c7d514647)
add release-0.3 to appveyor

modify msys_build.sh to download release installer instead of nightly

remove commented-out MSVC parts

release-0.3 uses utf8proc instead of mojibake
Add AppVeyor build status badge

modify status badges for release-0.3 branch
Merge pull request #9173 from JuliaLang/tk/backport-appveyor

RFC: backport appveyor to release-0.3