buildsystem: improve recursive dependenc handling

Signed-off-by: Andrew 'Necromant' Andrianov <andrew@ncrmnt.org>
msp430: fix startup code for ANTARES_* macros

Signed-off-by: Andrew 'Necromant' Andrianov <andrew@ncrmnt.org>
avr,msp430,generic: fix startup code and stubs

Signed-off-by: Andrew 'Necromant' Andrianov <andrew@ncrmnt.org>
scripts: add avrsz

Signed-off-by: Andrew 'Necromant' Andrianov <andrew@ncrmnt.org>