WIP: upgrade fsxc #3962

Job	Run time
linux-github--dotnet-and-mono	4m 23s
linux-vanilla--stockdotnet6-and-newmono	5m 20s
linux-vanilla--newmono-only	9m 6s
linux-github--dotnet-and-newmono	7m 28s
linux-vanilla--stockdotnet6-and-stockmono	6m 24s
linux-vanilla--stockdotnet6-only	4m 40s
linux-vanilla--stockmono-only	6m 12s
macOS--dotnet6-and-mono	13m 3s
macOS--dotnet6-only	4m 38s
macOS--mono-only	12m 35s
windows--dotnet6-and-legacyFramework	4m 39s
windows--dotnet6-only	5m 44s
windows--legacyFramework-only	10m 40s
conventions	0s
snap_pkg_beta	0s
snap_pkg	0s
	1h 34m 52s

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