For each link given as http://, verify that the site is accessible over
https:// and, if so, switch to it. These domains were converted:
* llvm.org
* clang.llvm.org
* en.cppreference.com
* www.dxx-rebirth.com
* www.libsdl.org
* www.scons.org
Only one caller exists, and that caller alway passes a non-nullptr
value. Switch to a reference and remove the unused special case to
handle a nullptr input.
Most uses pass an orientation matrix. All sites are deterministic about
whether a matrix is passed. Make the matrix mandatory for sites that
passed it, and split out a separate version of g3_start_instance_matrix
for the 2 sites which do not provide orientation.