gdb sandbox can cause issues with gdb and glibc

Now that bug 1517257 is resolved and apport uses a sandbox with the release's latest version of gdb to retrace a crash we encountered a case where the retracers were hanging attempt to retrace a crash.

Come to find out this is because gdb depends on libc6 and the version of glibc installed in the sandbox was the latest one (because of the dependency) yet the crash report was using the older version of libc6 and gdb hung when loading the core file.

While we worked around this by deleting all the core files with an old version of libc6 it'd be better if gdb did not hang or apport gave up after a while.

bdmurray@clean-xenial-amd64:~$ LD_LIBRARY_PATH=/tmp/apport_sandbox_gepsxaz0/lib:/tmp/apport_sandbox_gepsxaz0/lib/x86_64-linux-gnu:/tmp/apport_sandbox_gepsxaz0/usr/lib/x86_64-linux-gnu:/tmp/apport_sandbox_gepsxaz0/usr/lib PYTHONHOME=/tmp/apport_sandbox_gepsxaz0/usr GCONV_PATH=/tmp/apport_sandbox_gepsxaz0/usr/lib/x86_64-linux-gnu/gconv /tmp/apport_sandbox_gepsxaz0/lib/x86_64-linux-gnu/ld-linux-x86-64.so.2 /tmp/apport_sandbox_gepsxaz0/usr/bin/gdb --ex "set debug-file-directory /tmp/apport_sandbox_gepsxaz0/usr/lib/debug" --ex "set solib-absolute-prefix /tmp/apport_sandbox_gepsxaz0" --ex "add-auto-load-safe-path /tmp/apport_sandbox_gepsxaz0" --ex "set solib-search-path /tmp/apport_sandbox_gepsxaz0/lib/x86_64-linux-gnu" --ex "set data-directory /tmp/apport_sandbox_gepsxaz0/usr/share/gdb" --ex "file /tmp/apport_sandbox_gepsxaz0//usr/bin/xeyes"
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Reading symbols from /tmp/apport_sandbox_gepsxaz0//usr/bin/xeyes...Reading symbols from /tmp/apport_sandbox_gepsxaz0/usr/lib/debug/.build-id/2d/f8e1beb1c82d40e421cdfc96ac0b0ac992ed44.debug...done.
done.
(gdb) core-file /home/bdmurray/tmpD3ptDx-swift.5c645044-2799-11e8-9dd4-fa163e5006ec.oopsid.core
[New LWP 7620]
warning: .dynamic section for "/tmp/apport_sandbox_gepsxaz0/lib/x86_64-linux-gnu/libm.so.6" is not at the expected address (wrong library or version mismatch?)
warning: .dynamic section for "/tmp/apport_sandbox_gepsxaz0/lib/x86_64-linux-gnu/libdl.so.2" is not at the expected address (wrong library or version mismatch?)
warning: .dynamic section for "/tmp/apport_sandbox_gepsxaz0/lib/x86_64-linux-gnu/ld-2.27.so" is not at the expected address (wrong library or version mismatch?)
warning: .dynamic section for "/tmp/apport_sandbox_gepsxaz0/lib/x86_64-linux-gnu/librt.so.1" is not at the expected address (wrong library or version mismatch?)
warning: .dynamic section for "/tmp/apport_sandbox_gepsxaz0/lib/x86_64-linux-gnu/libpthread.so.0" is not at the expected address (wrong library or version mismatch?)