add pool alloc counter ctl

[lplewa]

Description

Checklist

• Code compiles without errors locally
• All tests pass locally
• CI workflows execute properly

• CI workflows, not executed per PR (e.g. Nightly), execute properly
• New tests added, especially if they will fail without my changes
• Added/extended example(s) to cover this functionality
• Extended the README/documentation
• All newly added source files have a license
• All newly added source files are referenced in CMake files
• Logger (with debug/info/... messages) is used
• All API changes are reflected in docs and def/map files, and are tested

[bratpiorka]

LGTM but formatting could be improved (empty lines, comments)

[Copilot]

Pull Request Overview

Adds a new allocation counter control (alloc_count) to the UMF memory pool API and tests.

• Introduce stats.alloc_count to track active allocations in each pool
• Register a new CTL subtree under umf.pool.by_handle.stats.alloc_count
• Update all alloc/free/realloc APIs to atomically increment/decrement the counter, and add a parameterized test

Reviewed Changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 3 comments.

File	Description
test/poolFixtures.hpp	New ctl_stat_alloc_count test to verify allocation counts
test/common/pool.hpp	Ignore aligned‐alloc support on Windows via #ifdef _WIN32
src/memory_pool_internal.h	Add umf_pool_stats_t and stats field to umf_memory_pool_t
src/memory_pool.c	Implement CTL handler, wire up alloc_count, update alloc/free/realloc

Comments suppressed due to low confidence (1)

src/memory_pool_internal.h:41

• [nitpick] Consider using a struct default initializer for stats (e.g. umf_pool_stats_t stats = {0};) to avoid the explicit memset in the create path.

    memset(&pool->stats, 0, sizeof(pool->stats));

[KFilipek]

Good job well done