Merge : re-applies missing part of fix for Bug 2901,Add export for s60ibymacros.pm
VARIANT A2EXTENDS groupAVIRTUALBUILD_INCLUDE set /epoc32/include/A2/buildBUILD_INCLUDE append /epoc32/include/A2/build2ROM_INCLUDE set /epoc32/include/A2/romVARIANT_HRH /epoc32/include/e32std.h