t/io_uring: add symbolic defines for NOP flags #937

Job	Run time
build-containers (debian, debian, bookworm, x86_64)	12m 37s
build (linux-gcc)	13m 22s
build (linux-clang)	12m 48s
build-containers (fedora, fedora, 40, x86_64)	14m 23s
build (macos)	16m 4s
build-containers (alma, almalinux, 9, x86_64)	14m 14s
build (linux-i686-gcc)	13m 8s
build-containers (oracle, oraclelinux, 9, x86_64)	14m 26s
build (android)	37s
build-containers (rocky, rockylinux, 9, x86_64)	14m 8s
build (windows-cygwin-64)	15m 52s
build-containers (ubuntu, ubuntu, noble, i686)	13m 11s
build (windows-cygwin-32)	16m 1s
build-containers (ubuntu, ubuntu, noble, x86_64)	13m 29s
build (windows-msys2-64)	13m 12s
build (android-recovery, ubuntu-22.04, aarch64-linux-android32)	37s
	3h 18m 9s

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