Examples: imgui_impl_opengl3 Fix GLAD error condition (#2059, #2002)
Examples: imgui_impl_opengl3 Fix GLAD error condition (#2059, #2002)

`gladLoadGL` returns 0 on fail, not the other way around.

burningreggae/imgui,Flix01/imgui,ocornut/imgui,aimotive/imgui-glfw,dougbinks/imgui,aimotive/imgui-glfw,bkaradzic/imgui,cmaughan/imgui,cmaughan/imgui,nProtect/imgui,Flix01/imgui,cmaughan/imgui,ocornut/imgui,ggtucker/imgui,ggtucker/imgui,bkaradzic/imgui,ocornut/imgui,bkaradzic/imgui,nProtect/imgui,dougbinks/imgui,cmaughan/imgui,Flix01/imgui,nProtect/imgui,burningreggae/imgui,ggtucker/imgui