1.5.1 (stable)

Changes since 1.5.0:

• Do no add pkg-config dependencies on gl on systems that do not use
  pkg-config, like macOS and Windows [Tom Schoonjans, #156]
• Generalise checks for dlvsym [Ross Burton, #158]
• Add an option for disabling building the test suite [Ross Burton]
• Typo fixes in the comments and documentation [luz.paz, #159]
• Simplify the Meson configuration logic for EGL and GLX [Eric
  Engestrom, #162]
• Use assert when no context is found [Adam Jackson, #166]
• Remove a test superceded by GLVND [#165]
• Avoid Meson warnings when testing for linker arguments