Missing find_dependency(uring) in RocksDBConfig.cmake

[yurybura]

Expected behavior

RocksDBConfig.cmake.in should be modified to find io_uring library if WITH_LIBURING=ON.
Also, WITH_LIBURING should be OFF on unsupported platforms, e.g. Windows.

Actual behavior

The io_uring dependency is added to the main CMakeLists.txt file, but the find_dependency(uring) is missing from the installed RocksDBConfig.cmake file:

rocksdb/CMakeLists.txt

Lines 314 to 320 in 05c3b8e

	if (WITH_LIBURING)
	find_package(uring)
	if (uring_FOUND)
	add_definitions(-DROCKSDB_IOURING_PRESENT)
	list(APPEND THIRDPARTY_LIBS uring::uring)
	endif()
	endif()

Steps to reproduce the behavior

1. Build RocksDB on Linux with liburing installed.
2. Build a simple program:

project(foo)
find_package(RocksDB CONFIG)
add_executable(foo main.cpp)
target_link_libraries(myprog PRIVATE RocksDB::rocksdb)

[cmake] CMake Error at <path>/RocksDBTargets.cmake:60 (set_target_properties):
[cmake] The link interface of target "RocksDB::rocksdb" contains:
[cmake]
[cmake] uring::uring
[cmake]
[cmake] but the target was not found. Possible reasons include:
[cmake]
[cmake] * There is a typo in the target name.
[cmake] * A find_package call is missing for an IMPORTED target.
[cmake] * An ALIAS target is missing.
[cmake]