macOS supports the OpenGL core profiles where glGetString(GL_EXTENSIONS)
is not supported. Use glGetStringi(GL_EXTENSIONS, <index>) instead.
The wrong query didn't make any practical difference because Gio doesn't
need any extensions on OpenGL 3 and better.
Signed-off-by: Elias Naur <mail@eliasnaur.com>
The `gogio` tool adds the `-fmodules -fobjc-arc` flags to the Cgo
C flags. Unfortunately, that masks problems where Cgo packages
accidentally didn't have the flags in their #cgo directives such
as package log.
Move the flags so they're only explicitly mentioned when `gogio`
invokes the host compiler to build the `main.m` shim.
Fix package log to include the missing flags.
While we're here, silence OpenGL ES deprecation warnings on iOS, just
as we do for macOS. The warnings are normally not visible because
the gogio tool suppress output from the go tool.
Signed-off-by: Elias Naur <mail@eliasnaur.com>