compiler: don't treat methods without self node (static class methods, class contructors, destructors, operators) as method pointers, fix comparison of procdef and procvardef to allow assignment of a static class method to a regular procedural variable (issue #24486)

git-svn-id: http://svn.freepascal.org/svn/fpc/trunk@25284 3ad0048d-3df7-0310-abae-a5850022a9f2