Add always_inline to ctor/dtor in opengl.cpp
Add always_inline to ctor/dtor in opengl.cpp

Avoid COMDAT errors in some Mac build configs


Former-commit-id: 4ab2cfa290080b351e45e84e153a16b9bd288f55
darkbuck/Halide,Trass3r/Halide,darkbuck/Halide,Trass3r/Halide,Trass3r/Halide,darkbuck/Halide,darkbuck/Halide,Trass3r/Halide,darkbuck/Halide,Trass3r/Halide,darkbuck/Halide,Trass3r/Halide,Trass3r/Halide,darkbuck/Halide