Remove redundant a_generic kernels #731

Job	Run time
build-windows	3m 33s
Build on ubuntu-20.04 g++-7	1m 38s
Build on ubuntu-20.04 g++-8	1m 36s
Build on ubuntu-latest g++-9	1m 47s
Build on ubuntu-latest g++-10	1m 29s
Build on ubuntu20.04 aarch64 g++-8	12m 29s
Build on ubuntu20.04 aarch64 g++-9	8m 51s
Build on ubuntu-20.04 clang-7	1m 32s
Build on ubuntu20.04 aarch64 g++-10	11m 24s
Build on ubuntu22.04 aarch64 g++-12	9m 27s
Build on ubuntu-20.04 clang-8	1m 38s
Build on ubuntu20.04 aarch64 clang-9	15m 33s
Build on ubuntu-20.04 clang-9	1m 18s
Build on ubuntu-20.04 clang-10	1m 34s
Build on ubuntu20.04 aarch64 clang-10	16m 16s
Build on ubuntu-20.04 clang-11	1m 13s
Build on ubuntu22.04 aarch64 clang-14	21m 3s
Build on ubuntu22.04 armv7 g++-12	8m 16s
Build on ubuntu-latest clang-12	1m 18s
Build on ubuntu22.04 ppc64le g++-12	10m 42s
Build on ubuntu-latest clang-13	1m 31s
Build on ubuntu22.04 s390x g++-12	9m 41s
Build on ubuntu-latest clang-14	1m 36s
Build on ubuntu22.04 riscv64 g++-12	10m 1s
build-macos	1m 18s
Build static on ubuntu-latest	1m 46s
	2h 38m 30s

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