tweaks to mingw build environment
Revert "tweaks to mingw build environment"

This reverts commit fa09121a7f20ba424df5b9542564a467af63dc7a.
Revert "Build system changes to support mingw build target"

This reverts commit 94145732f3bd406ec75652117c02c8aaab6777ca.
(reapply with fixes) Build system changes to support mingw build target
Disable check for boost with mingw build
Update mingw environment to work with mingw-64 toolchain on F17