minorfix(imscope): moving alignas from struct type to atomic variable

[turkeryilmaz]

I was receiving the note below when I built with "imscope_record", so this is the simplest PR to avoid the psABI note while signing the new individual CLA.

[194/11156] Building CXX object openair1/PHY/TOOLS/imscope/CMakeFiles/imscope_record.dir/imscope_record.cpp.o
In file included from /home/turker/Documents/OpenAirInterface/26w25/openair1/PHY/defs_nr_UE.h:12,
from /home/turker/Documents/OpenAirInterface/26w25/openair1/PHY/TOOLS/imscope/imscope_internal.h:12,
from /home/turker/Documents/OpenAirInterface/26w25/openair1/PHY/TOOLS/imscope/imscope_record.cpp:5:
/usr/include/c++/13/atomic: In member function ‘_Tp std::atomic<_Tp>::exchange(_Tp, std::memory_order) [with _Tp = ImScopeDumpInstruction]’:
/usr/include/c++/13/atomic:311:7: note: the ABI for passing parameters with 64-byte alignment has changed in GCC 4.6
311 | exchange(_Tp __i, memory_order __m = memory_order_seq_cst) noexcept
| ^~~~~~~~

[linux-foundation-easycla]

The committers listed above are authorized under a signed CLA.

• ✅ login: turkeryilmaz / name: Turker Yilmaz (5a963bd)

[durantabot]

CI Build: #495 | Not performing CI due to the absence of one of the following mandatory labels:

• documentation Documentation-related changes or updates. (don't perform any stages)
• BUILD-ONLY Execute build stages only for code improvements with no impact on 4G/5G functionality. (execute only build stages)
• 4G-LTE Perform 4G Tests (perform 4G tests)
• 5G-NR Perform 5G Tests (perform 5G tests)
• nrUE Run only 5G UE tests (physims included, LDPC tests excluded). (perform only 5G-UE related tests including physims excluding LDPC tests)
• CI Perform both 4G and 5G tests (perform both 4G and 5G tests)

[rorsc]

@turkeryilmaz you are missing the signed-off-by commit trailer, please add with git commit -s