cmd/link: new test TestFlagW is not applicable to platforms without DWARF

[millerresearch]

CL 703998 introduced cmd/link.TestFlagW which is only applicable to platforms with DWARF (as the commit message acknowledges), and therefore fails on Plan 9. Example failure is here:

--- FAIL: TestFlagW (54.37s)
--- FAIL: TestFlagW/-s_-w=0 (17.45s)
    dwarf_test.go:401: want binary with DWARF, got error no DWARF data in Plan 9 file
FAIL
FAIL	cmd/link	210.484s

The test should be conditional on internal/platform.ExecutableHasDWARF, like other DWARF tests in this module.

[gabyhelp]

Related Issues

• cmd/link: TestDWARF failing on non-cgo platforms #19793 (closed)
• cmd/link: TestRuntimeTypeDIEs failing on Plan 9 #19944 (closed)
• cmd/link: TestSizes failing on Plan 9 #21453 (closed)
• cmd/link: TestFieldOverlap failing on Plan 9 #21480 (closed)
• cmd/compile: TestEmptyDwarfRanges failing on Plan 9 #24226 (closed)

Related Code Changes

• cmd/link: skip TestDWARF on Plan 9
• cmd/go: disable compiler DWARF generation on some platforms
• cmd/compile: skip TestEmptyDwarfRanges on Plan 9
• [release-branch.go1.8] cmd/link: skip TestDWARF on Plan 9
• cmd/link: skip TestSizes on Plan 9

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[gopherbot]

Change https://go.dev/cl/706418 mentions this issue: cmd/link: skip TestFlagW on platforms without DWARF symbol table