lib min_heap: use size_t for array size and index variables

lib min_heap: use size_t for array size and index variables

Replace the int type with size_t for variables representing array sizes
and indices in the min-heap implementation.  Using size_t aligns with
standard practices for size-related variables and avoids potential issues
on platforms where int may be insufficient to represent all valid sizes or
indices.

Link: https://lkml.kernel.org/r/20250215165618.1757219-1-visitorckw@gmail.com
Signed-off-by: Kuan-Wei Chiu <visitorckw@gmail.com>
Cc: Ching-Chun (Jim) Huang <jserv@ccns.ncku.edu.tw>
Cc: Yu-Chun Lin <eleanor15x@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>