Hello,

# [GNU-767] Support changing SVE vector length in remote debugging

* Debugged and fixed a few issues in my code where gdbserver was having trouble with setting the target description for new threads. Also fixed regressions in a couple more testcases.

# Linaro CI's GDB testsuite results

* Luis commented on IRC that the GDB testsuite results from the Linaro CI seemed a bit high with about 540 failures, so I set out to investigate. The two biggest sources of failures are:

1. Ada tests were failing because they can't build their test executables. This is expected because we don't have the Ada compiler in the CI, but normally these testcases would just bail out as unsupported. Found out that there was a regex in the GDB testsuite that was (IMHO) too strict for our particular setup and fixed it.

2. All CTF tests are failing. The compiler in the CI seems to be building test executables with CTF debug info, so we do seem to have a problem there.

The CI's GDB is also not loading libthread_db.so because of a GDB security setting, so I fixed that as well and expect some more tests to pass now.

I still haven't submitted my fixes for 1. to upstream and for the libthread_db.so.1 issue to our CI scripts because I'm still working with jenkins-scripts and Abe to reproduce the CI environment to verify the fixes.