GPU/TPC: Encode saturated qTot and tailLength in ClusterNative

[fweig]

No description provided.

[alibuild]

Error while checking build/O2/fullCI_slc9 for 81779eb at 2026-06-02 18:13:

## sw/BUILD/O2-latest/log
/sw/SOURCES/O2/slc9_x86-64-slc9_x86-64/0/DataFormats/Detectors/TPC/include/DataFormatsTPC/ClusterNative.h:66:43: error: use of undeclared identifier 'UINT16_MAX'
/sw/SOURCES/O2/slc9_x86-64-slc9_x86-64/0/DataFormats/Detectors/TPC/include/DataFormatsTPC/ClusterNative.h:93:23: error: use of undeclared identifier 'UINT16_MAX'
/sw/SOURCES/O2/slc9_x86-64-slc9_x86-64/0/DataFormats/Detectors/TPC/include/DataFormatsTPC/ClusterNative.h:93:44: error: use of undeclared identifier 'UINT16_MAX'
ninja: build stopped: subcommand failed.

Full log here.

[alibuild]

Error while checking build/O2/fullCI_slc9 for 2afd294 at 2026-06-02 19:49:

## sw/BUILD/O2Physics-latest/log
c++: fatal error: Killed signal terminated program cc1plus
ninja: build stopped: subcommand failed.

Full log here.

[davidrohr]

O2 seems to compile now. Is the O2Physics error unrelated? Then we could squash-merge it.