+ added optional Tasmsymtype parameter to TAsmData.RefAsmSymbol and WeakRefAsmSymbol to allow specifying things like AT_DATA for external symbols that reside in the data segment, which is needed for i8086 medium and compact memory models

git-svn-id: http://svn.freepascal.org/svn/fpc/trunk@25242 3ad0048d-3df7-0310-abae-a5850022a9f2