const compress/flate.inputMargin

3 uses

	compress/flate (current package)
		deflatefast.go#L46: 	inputMargin            = 16 - 1
		deflatefast.go#L47: 	minNonLiteralBlockSize = 1 + 1 + inputMargin
		deflatefast.go#L86: 	sLimit := int32(len(src) - inputMargin)