libuv: updated to 1.38.0

Version 1.38.0
* test: skip poll_duplex and poll_unidirectional on PASE
* linux: make cpu_times consistently be milliseconds
* win: DRY uv_poll_start() and uv_poll_stop()
* win: DRY uv_poll_close()
* unix,win: add uv_library_shutdown()
* unix: yield cpu when spinlocking on async handle
* win: remove dep on GetQueuedCompletionStatusEx
* doc: correct source lines
* build,android: fix typo
* doc: uv_cancel() handles uv_random_t requests
* doc: fix unescaped character
* build,cmake: fix compilation on old MinGW
* build: remove unnessesary MSVC warnings
* win: make uv_udp_init_ex() accept UV_UDP_RECVMMSG
* unix: simplify uv__udp_init_ex()
* win: remove MAX_PATH limitations
* build, win: add long path aware manifest
* doc: check/idle/prepare functions always succeed
* darwin: fix build with non-apple compilers
* win: support environment variables > 32767 chars
* unix: fully initialize struct msghdr
* doc: add uv_replace_allocator thread safety warning
* unix: fix int overflow when copying large files
* fs: report original error
* win, fs: add IO_REPARSE_TAG_APPEXECLINK support
* doc: fix formatting
* unix: fix memory leak when uv_loop_init() fails
* unix: shrink uv_udp_set_source_membership() stack
* unix,win: fix wrong sizeof argument to memcpy()
* build: check for libraries not provided by libc
* doc: fix the order of arguments to calloc()
* unix: don't abort when getrlimit() fails
* test: support common user profile on IBMi
* build: test on more platforms via QEMU in CI

(adam)