Running Thunderbird with the OpenPower Baseline JIT

The issues with Ion and Wasm in OpenPower Firefox notwithstanding, the Baseline JIT works well in Firefox ESR128, and many of you use it (including yours truly). Of course, that makes Thunderbird look sluggish without it. I wasn't able to get a full LTO-PGO build for Thunderbird to build properly so far with gcc (workin' on it), but with the JIT patches for ESR128 an LTO optimized build will…