lint: don't use -unused.whole-program when PKG is specified

[stevendanna]

The unused linter's whole program mode will create false-positives
when PKG is specified. As a result, anyone trying to use

make lint PKG=./pkg/SOMETHING

has to carefully read the failure output to see if it was actually a
success. By not passing that flag when PKG is specified, more cases of
the above command complete without erroneous findings.

Release note: None

[cockroach-teamcity]

This change is 

[HonoreDB]

---

pkg/testutils/lint/lint_test.go, line 1615 at r1 (raw file):

			args = []string{pkgScope}
		} else {
			args = []string{"-unused.whole-program", pkgScope}

Isn't pkgScope empty in this case anyway?

[stevendanna]

Isn't pkgScope empty in this case anyway?

I don't think so:

cockroach/pkg/testutils/lint/lint_test.go

Lines 1404 to 1408 in f49997b

	// Things that are packaged scoped are below here.
	pkgScope := pkgVar
	if !pkgSpecified {
	pkgScope = "./pkg/..."
	}

[HonoreDB]

Reviewable status: complete! 1 of 0 LGTMs obtained (waiting on @stevendanna)

[stevendanna]

bors=HonoreDB

[stevendanna]

bors r=HonoreDB

[craig]

Build failed (retrying...):

• GitHub CI (Cockroach)

[craig]

Build succeeded:

• GitHub CI (Cockroach)