mac: Fix build with 10.9 SDK

Without this, the compiler complains about GL_TEXTURE_RECTANGLE_ARB etc not being declared.
(similar to fix in upstream commit f52fe5854ece2fe8ff5093060e2274972311d083)
Merge pull request #23 from fancycode/opengl_osx_109

mac: Fix build with 10.9 SDK
enable command line support for "high-dpi-support"

Part of rogerwang/node-webkit#2524
add switch kHighDPISupport
[Linux] set initial size hints for non-resizable window

Part of rogerwang/node-webkit#2319