GL capability: AND the fragment coverage with the temporary coverage value

Foreign: GL_SAMPLE_COVERAGE

Property definitions

glesv2 $ GLCapabilities :: sample_coverage=
	# GL capability: AND the fragment coverage with the temporary coverage value
	#
	# Foreign: GL_SAMPLE_COVERAGE
	var sample_coverage: GLCap is lazy do return new GLCap(0x80A0)
lib/glesv2/glesv2.nit:1125,2--1128,63