[avr-gcc-list] avrtest core simulator updated to avrxmega6

[Georg-Johann Lay]

FYI, I updated the avrtest core simulator hosted in the WinAVR project 
at sourceforge.  The avrtest simulator can now be used to reg-test 
avr-gcc testsuite against xmega core.

As target I used atxmega128a3 and the test results are exactly the same
as for atmega128, except for some functions that use builtin return or
instrument-functions that trigger builtin return.

This is because flash size of atxmega128a3 is > 64Ki words, thus a 
warning from avr.c

warning: 'builtin_return_address' contains only 2 bytes of address

I did not try to use PSImode as potential fix; but even with PSImode
there would be a warning from the assembler like

.warning "assembling 24-bit address needs binutils extension for
         " hh8(<symbol>)"

The simulator does not test I/O and the new operand modifier %i, of
course, but I heard that guys using 4.7 snapshots could compile and run
xmega programs without problems.

Johann