Fix the char overload for testing printers under C++. #306

Job	Run time
build (ubuntu-latest, Debug, clang)	26s
build (ubuntu-latest, Debug, gcc)	27s
build (ubuntu-latest, Debug, tcc)	20s
build (ubuntu-latest, RelWithDebInfo, clang)	31s
build (ubuntu-latest, RelWithDebInfo, gcc)	29s
build (ubuntu-latest, RelWithDebInfo, tcc)	29s
build (ubuntu-latest, MinSizeRel, clang)	30s
build (ubuntu-latest, MinSizeRel, gcc)	26s
build (ubuntu-latest, MinSizeRel, tcc)	22s
build (ubuntu-latest, Release, clang)	50s
build (ubuntu-latest, Release, gcc)	30s
build (ubuntu-latest, Release, tcc)	25s
build (windows-latest, Debug, default)	52s
build (windows-latest, Debug, clang)	2m 20s
build (windows-latest, Debug, gcc)	3m 1s
build (windows-latest, RelWithDebInfo, default)	1m 50s
build (windows-latest, RelWithDebInfo, clang)	1m 43s
build (windows-latest, RelWithDebInfo, gcc)	3m 6s
build (windows-latest, MinSizeRel, default)	44s
build (windows-latest, MinSizeRel, clang)	2m 2s
build (windows-latest, MinSizeRel, gcc)	2m 16s
build (windows-latest, Release, default)	1m 16s
build (windows-latest, Release, clang)	2m 2s
build (windows-latest, Release, gcc)	3m 25s
build (macos-13, Debug, default)	24s
build (macos-13, RelWithDebInfo, default)	47s
build (macos-13, MinSizeRel, default)	45s
build (macos-13, Release, default)	37s
build (macos-latest, Debug, default)	11s
build (macos-latest, RelWithDebInfo, default)	16s
build (macos-latest, MinSizeRel, default)	16s
build (macos-latest, Release, default)	16s
	33m 54s

Provide feedback