Update to 2.18.4.

• Do not complain about icon installation if USE_QT is defined [1]
• Add support for checking LICENSE_PERMS [2]
• Add a warning when NO_PACKAGE is used [2]
• Per the Porter's handbook, check for sections for USE/USES and FLAVORS [3]
• Check for -on/-off in OPTION names [4]
• Check to make sure the correct LICENSE_FILE_foo is specified [5]

PR: 231122 [1]

		231155 [2]
		230594 [3]
		229280 [4]
		231303 [5]

Submitted by: loader [3]

		adamw [4]