debug/macho: filter non-external symbols when reading imported symbols without LC_DYSYMTAB
File.ImportedSymbols will return symbols with a type that has one of the
N_STAB (0xe0) bits set and no section. That's not the expected behavior,
as those symbols might not be external.
We should expand the type check to also account for the N_EXT bit.
The section check is not necessary, as N_EXT symbols never have it set.
I have found this issue in the wild by running "go tool cgo -dynimport",
but unfortuantely I couldn't get a minimal C code that generates
N_STAB symbols without section, so this CL doesn't add any new test.
Change-Id: Ib0093ff66b50c7cc2f39d83936314fc293236917
Reviewed-on: https://go-review.googlesource.com/c/go/+/702296 Reviewed-by: Cherry Mui <cherryyz@google.com> Reviewed-by: David Chase <drchase@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>