Do not define our own mpfr_sinpi/mpfr_cospi for mpfr 4.2.0 and later … #24

Job	Run time
build-native-gcc	5m 33s
build-native-llvm	5m 51s
test-native-gcc	9m 3s
build-aarch64-gcc	8m 18s
test-native-llvm	9m 15s
build-aarch64-llvm	3m 31s
build-armhf-gcc	1m 57s
build-armhf-llvm	1m 24s
build-ppc64el-gcc	6m 34s
build-ppc64el-llvm	4m 43s
build-s390x-gcc	3m 44s
build-s390x-llvm	2m 12s
build-riscv64-llvm	1m 46s
test-aarch64-gcc (qemu_cpu: "max,sve=off")	16m 38s
test-aarch64-gcc (qemu_cpu: "max,sve=on,sve128=on")	25m 29s
test-aarch64-gcc (qemu_cpu: "max,sve=on,sve256=on")	25m 24s
test-aarch64-gcc (qemu_cpu: "max,sve=on,sve512=on")	29m 39s
test-armhf-gcc (qemu_cpu: "max")	17m 25s
test-armhf-llvm (qemu_cpu: "max")	15m 48s
test-ppc64el-gcc (qemu_cpu: "power10")	29m 47s
test-ppc64el-llvm (qemu_cpu: "power10")	24m 22s
test-s390x-gcc (qemu_cpu: "")	19m 22s
test-s390x-llvm (qemu_cpu: "")	21m 43s
test-riscv64-llvm (qemu_cpu: "rv64,zba=true,zbb=true,zbs=true,v=false")	5m 12s
test-riscv64-llvm (qemu_cpu: "rv64,zba=true,zbb=true,zbs=true,v=true,vlen=128,elen=64,vext_spec=v1.0")	16m 15s
test-riscv64-llvm (qemu_cpu: "rv64,zba=true,zbb=true,zbs=true,v=true,vlen=256,elen=64,vext_spec=v1.0")	19m 56s
test-riscv64-llvm (qemu_cpu: "rv64,zba=true,zbb=true,zbs=true,v=true,vlen=512,elen=64,vext_spec=v1.0")	31m 18s
	6h 2m 9s

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