cmd/link: debug_line can contain multiple entries for the same PC address in Go 1.15.4 [1.15 backport]

[gopherbot]

@thanm requested issue #42484 to be considered for backport to the next 1.15 minor release.

@gopherbot please open a backport issue for 1.15.

[gopherbot]

Change https://golang.org/cl/269517 mentions this issue: [release-branch.go1.15] cmd/compile: do not emit an extra debug_line entry for the end of seq addr

[gopherbot]

Change https://golang.org/cl/269518 mentions this issue: [release-branch.go1.15] cmd/compile: do not emit an extra debug_line entry for the end of seq addr

[dmitshur]

Approved as this is a serious issue without a viable workaround. Only 1.15 needs this backport.

[gopherbot]

Closed by merging 16ddb8b to release-branch.go1.15.