This PR makes possible to build the qt package in depends against libc++ for x86_64 platform.
Fixes #22344.
Required for #22815.
Also this PR fixes the [no wallet] [bionic] task on CI:
- on master (a8bbd4cc819633ec50ed0f763b6a75330ae055fb), https://api.cirrus-ci.com/v1/task/5558609250615296/logs/ci.log:
0Options used to compile and link:
1  external signer = yes
2  multiprocess    = no
3  with libs       = yes
4  with wallet     = no
5  with gui / qt   = no
0Options used to compile and link:
1  external signer = yes
2  multiprocess    = no
3  with libs       = yes
4  with wallet     = no
5  with gui / qt   = yes