[next] Revert GCC 11 'Default to DWARF5'
[next] Revert GCC 11 'Default to DWARF5'

GCC 11 defaults to DWARF5. This causes problems with tools that are not
ready for it.  In particular, `perf` on SLES 15 SP2:
```
$rpm -qi perf
Name        : perf
Version     : 5.3.18
Release     : 23.24
```

Pull request #1928 hit this issue, seeing the FVTR test for `perf`
hang at the command:
```
$ perf probe -v -x /path/to/AT/at-next-15.0-0-alpha/bin/ld test_perf_debug=main argc
probe-definition(0): test_perf_debug=main argc
symbol:main file:(null) line:0 offset:0 return:0 lazy:(null)
parsing arg: argc into argc
1 arguments
Open Debuginfo file: /path/to/AT/at-next-15.0-0-alpha/bin/ld
Try to find probe point from debuginfo.
```

Revert the subject patch at least until these tools are ready.

Fixes #1951

Signed-off-by: Paul A. Clarke <793d6d7c60bd6329d6f91fdb8c1b53aab99bf3da@us.ibm.com>

advancetoolchain/advance-toolchain,advancetoolchain/advance-toolchain,advancetoolchain/advance-toolchain,advancetoolchain/advance-toolchain,advancetoolchain/advance-toolchain,advancetoolchain/advance-toolchain