Fuzz

Allow separate header usage and test all includes #682

Job	Run time
posix (clang, clang++-12, 14,17,20, ubuntu-22.04, clang-12)	12m 9s
posix (clang, clang++-13, 14,17,20, ubuntu-22.04, clang-13)	7m 46s
posix (clang, clang++-14, 14,17,20, ubuntu-22.04, clang-14)	8m 0s
posix (clang, clang++-14, 14-gnu,17-gnu,20-gnu, ubuntu-22.04, clang-14)	7m 56s
posix (clang, clang++-15, 14,17,20, ubuntu-22.04, clang-15, deb http://apt.llvm.org/jammy/ llvm-t...	7m 37s
posix (clang, clang++-16, 14,17,20, ubuntu-22.04, clang-16, deb http://apt.llvm.org/jammy/ llvm-t...	9m 33s
posix (clang, clang++-17, 14,17,20, ubuntu-22.04, clang-17, deb http://apt.llvm.org/jammy/ llvm-t...	8m 37s
posix (clang, clang++-18, 14,17,20,23, ubuntu-24.04, clang-18, deb http://apt.llvm.org/noble/ llv...	9m 54s
posix (clang, clang++-19, 14,17,20,23, ubuntu-24.04, clang-19, deb http://apt.llvm.org/noble/ llv...	11m 29s
	1h 23m 1s

Provide feedback