Fix issue #388

Description

• Newer Gawk (at least v5.1.0) will pre-compile the ratio ${peak_mem_sim_full} / ${peak_mem_no_sim} as a constant expression; if ${peak_mem_no_sim} == 0 this will then raise an awk: cmd. line:1: error: division by zero attempted error, even though the expression is never used as the if() condition is false
• Assigning those values to Gawk variables prevents the pre-compilation

Fixes #388 (closed)

API Changes and Justification

Backwards Compatible Changes

• This change introduces no API changes
• This change adds new API calls

Backwards Incompatible Changes

• This change modifies an existing API
• This change removes an existing API

Review Status

cc @adam-mercer @duncanmmacleod