The mcheck heap protection stores a caller string in each allocation
header for debugging purposes. The length is hard-coded to 48 bytes in
mcheck_core.inc.h
Add a CONFIG_MCHECK_CALLER_LEN Kconfig option to make this configurable,
allowing users to adjust the trade-off between the amount of debugging
context and the memory overhead per allocation.
Co-developed-by: Claude Opus 4.5 <noreply@anthropic.com>
Signed-off-by: Simon Glass <simon.glass@canonical.com>