Add long_tv unittest
Fix sc_val_to_long overflow
Fix undefined behavior: left shift of negative value
Handle complex initializers when determining 'address taken'.

This fixes opt/loadstore2.c.
bring back 0x prefix for tarval %+F printing
cleanup, fix usage of uninitialized values when calculating benefice of unused parameters
Try to make tarval_is_long() semantics more clear.
strcalc should not depend on ir_mode structure
fix tarval_is_long() edge cases, improve unittest