build: fix ios build error
build: fix ios build error

`_NSGetEnviron()` is not available on that platform.

PR-URL: https://github.com/libuv/libuv/pull/2449
Reviewed-By: Ben Noordhuis <59bd0a3ff43b32849b319e645d4798d8a5d1e889@bnoordhuis.nl>
Signed-off-by: MaYuming <c185c2c4aee99b3ac7ccb3f8bb4eebbffb7d6e62@appexnetworks.com>

unknownbrackets/maxcso,unknownbrackets/maxcso,unknownbrackets/maxcso,unknownbrackets/maxcso,unknownbrackets/maxcso,unknownbrackets/maxcso,unknownbrackets/maxcso