Port ngtcp2_ksl changes that introduced ngtcp2_ksl_search #829

Job	Run time
build (ubuntu-24.04, gcc, autotools)	1m 29s
build-cross (x86_64-w64-mingw32)	1m 22s
build (ubuntu-24.04, gcc, cmake)	49s
build-windows (x86)	1m 4s
build-cross (i686-w64-mingw32)	1m 24s
build-windows (x64)	59s
build (ubuntu-24.04, clang, autotools)	55s
build (ubuntu-24.04, clang, distcheck)	53s
build (ubuntu-24.04, clang, cmake)	1m 1s
build (macos-13, gcc, autotools)	1m 35s
build (macos-13, gcc, cmake)	1m 25s
build (macos-13, clang, autotools)	1m 15s
build (macos-13, clang, cmake)	1m 37s
build (macos-14, gcc, autotools)	39s
build (macos-14, gcc, cmake)	44s
build (macos-14, clang, autotools)	42s
build (macos-14, clang, cmake)	41s
release	0s
	18m 34s

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