rework of cluster manager. support additional launches via a worker
avoid the stack-smasher strcpy-alloca and minor cleanup
Revert "run win64 in parallel again on appveyor"

This reverts commit a297d5c816ef26274eb5e48e953eba1c3f2a8094.

Sadly issue #7942 is still a problem
Bump libgit2 to 0.21.3
Bump Windows PortableGit to 1.9.5

Bump git to 1.8.5.6 for Mac binaries

add checksums for git
Merge pull request #9309 from amitmurthy/amitm/cman_rework

rework of cluster manager. support additional launches via a worker
patch libgit2 so 0.21.3 can compile with mingw