build: fix cross-compiling for iOS
build: fix cross-compiling for iOS

Previously to build successfully for iOS, you needed to specify OS=mac
at gyp time.  This treats ios and mac as exactly the same.

PR-URL: https://github.com/libuv/libuv/pull/262
Reviewed-By: Saúl Ibarra Corretgé <8a7991f6950ea189abf159d6ec98d2fcc13dc5f6@gmail.com>

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