graphics/openshadinglanguage: update to 1.7.5

• Add indirect dependencies
• Convert USE_GCC to USES=compiler:c++11-lib
• Chase WWW redirect

Changes: https://github.com/imageworks/OpenShadingLanguage/raw/Release-1.7.5/CHANGES
PR: 216462
Submitted by: Shane <FreeBSD@ShaneWare.Biz> (maintainer)