...and now actually non-virtual

...as promised by 81c9fe933e4aed25b0fe801c1fea856f02381282 "Getter members of
VCLXGraphics not in XGraphics need not be virtual."

Change-Id: I18c89056af5d29504f107937b96af632887a4702
forward*PropertyValue functions need not be SAL_CALL

...and _bSuccess parameter is unused

Change-Id: Iee5e1d5c2d4272f342b2867bfe76f8c87dcd69d4