Resolve "replace L_shr_o by overflow-free alternatives"

Some Places need to be double checked: Is L_shr_o the better choice here?

1. swb_bwe_com_fx: exp2 is never negative

• L_shr_o will never shift to left, so will never overflow
• --> L_shr_o can be safely substituted with L_shr without hesitation

2. tools_fx: Calc_Energy_Autoscaled

• --> same as case 1) : substitute without hesitation

3. swb_bwe_enc_lr_fx:

• --> Overflow is read, afterwards, so L_shr_o is kept

Closes #1799 (closed)