runtime: TestGdbBacktrace failures

[gopherbot]

#!watchflakes
default <- pkg ~ `runtime` && test == "TestGdbBacktrace"

Issue created automatically to collect these failures.

Example (log):

=== RUN   TestGdbBacktrace
=== PAUSE TestGdbBacktrace
=== CONT  TestGdbBacktrace
    runtime-gdb_test.go:81: gdb version 10.1
    runtime-gdb_test.go:529: gdb output:
        Loading Go Runtime support.
        Breakpoint 1 at 0x46f040: file /home/swarming/.swarming/w/ir/x/t/TestGdbBacktrace3908509916/001/main.go, line 17.
    runtime-gdb_test.go:548: gdb exited with error: signal: aborted (core dumped)
--- FAIL: TestGdbBacktrace (1.11s)

— watchflakes

[gopherbot]

Found new dashboard test flakes for:

#!watchflakes
default <- pkg == "runtime:cpu4" && test == "TestGdbBacktrace"

2025-06-24 01:21 gotip-linux-amd64-longtest-noswissmap go@f8669582 runtime:cpu4.TestGdbBacktrace (log)

=== RUN   TestGdbBacktrace
=== PAUSE TestGdbBacktrace
=== CONT  TestGdbBacktrace
    runtime-gdb_test.go:81: gdb version 10.1
    runtime-gdb_test.go:529: gdb output:
        Loading Go Runtime support.
        Breakpoint 1 at 0x46f040: file /home/swarming/.swarming/w/ir/x/t/TestGdbBacktrace3908509916/001/main.go, line 17.
    runtime-gdb_test.go:548: gdb exited with error: signal: aborted (core dumped)
--- FAIL: TestGdbBacktrace (1.11s)

— watchflakes