Find address of reference to symbol by its name

[giulianobelinassi]

Before this patch, the user could only specify

 #target_symbol:target_symbol_ref:addr1:addr2

however, those address can change when you modify the livepatch sourcecode. Therefore, we now support:

 #target_symbol:target_symbol_ref

and now addr1 and addr2 will be collected analysing the target library and livepatch container automatically on packer time.

Signed-off-by: Giuliano Belinassi gbelinassi@suse.de