[configure/airtunes] - fixed typo
[configure/airtunes] - fix fallback to libshairport if libshairplay can't be found. Bail out if --enable-airtunes was given and none of both libs was found.
Merge pull request #3972 from Memphiz/fixshairportfallback

[configure/airtunes] - fix the fallback to libshairport if libshairplay can't be found...
Revert "[WIN32] changed: use up to 4 parallel msbuild workers."

This reverts commit 162347f2b027ad7b333c5864a4153c5ece7c754f.

This change works fine if the windows vm is the only one compiling. Since the recent build logs showed a longer compile time when doing builds for all platforms I'll revert this for now to see if it was the culprit.
AESinkPULSE: Initial Implementation