To prevent issues like #1786, run staticcheck on the primary GOOSes:
linux, mac, and windows.
Windows also has a fair amount of GOARCH-specific code.
If we ever have GOARCH staticcheck failures on other GOOSes,
we can expand the test matrix further.
This requires installing the staticcheck binary so that
we can execute it with different GOOSes.
Signed-off-by: Josh Bleecher Snyder <josharian@gmail.com>
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