Suppress false positive Valgrind warnings which flooded the output.
- BLI_mempool alloc/free & iteration.
- Set alignment padding bytes at the end of MEM_* allocations
as "defined" since this causes many false positive warnings
in blend file writing and MEMFILE comparisons.
- Set MEM_* allocations as undefined when `--debug-memory`
is passed in to account for debug initialization.
- Initialize pad bytes in TextLine allocations.
20fd012adb