examples/gl_basic: use native sleep functions
examples/gl_basic: use native sleep functions

nanosleep does not exist under Windows, use Sleep instead.

Signed-off-by: Emil Velikov <4c996f2f093ddd0585a556460b4cc3ba555546ef@gmail.com>
Reviewed-by: Brian Paul <3cb4e1df5ec4da2c7c4af7c52cec8cf340a55a10@vmware.com>
Reviewed-by: Jose Fonseca <61b5a29db2c0650f7c8510f93eece059c1b09320@vmware.com>
Reviewed-by: Chad Versace <a557f7f75bf28dc19ac99107f5cc7cd6b3fbdb1a@linux.intel.com>

fjhenigman/waffle,evelikov/waffle,waffle-gl/waffle,chadversary/waffle,chadversary/waffle,waffle-gl/waffle,fjhenigman/waffle,maurossi/waffle,maurossi/waffle,waffle-gl/waffle,dcbaker/waffle,waffle-gl/waffle,chadversary/waffle,evelikov/waffle,dcbaker/waffle,maurossi/waffle,evelikov/waffle,fjhenigman/waffle,dcbaker/waffle