Reject zero-size operation name buffers

[fallintoplace]

Summary

migraphx_operation_name accepted a non-null output pointer with out_size == 0, then computed out_size - 1 before copying the operation name. That underflowed the limit used by std::copy_n and could write past the caller's buffer.

This change rejects zero-size output buffers with migraphx_status_bad_param, updates the API generator so regenerated C API output keeps the same guard, and extends the C API operation-construction test to cover null output, zero size, truncation, and normal success.

Tests

• git diff --check
• python3 -m py_compile tools/api.py src/api/migraphx.py
• python3 tools/api.py src/api/migraphx.py tools/api/api.cpp | rg -n "migraphx_operation_name|Bad parameter out|Bad parameter out_size|copy_n" -C 3
• cc -fsyntax-only -I <temporary export-header include> -I src/api/include test/api/test_c_op_construct.c

Not run: full CMake/API test target. Local configure stops before target generation because ROCmCMakeBuildTools is not installed on this machine.

[github-actions]

Thank you for your contribution! Since this is an external pull request, a maintainer must review PR and add the "ok-to-test" label if it is approved for testing.

[pfultz2]

An empty string could be a valid input perhaps not in this case, but this makes it always a bad param everytime we take a string as input.

[pfultz2]

Ah wait, nevermind, this is for the output parameter not the input.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

Additional details and impacted files

@@           Coverage Diff            @@
##           develop    #4973   +/-   ##
========================================
  Coverage    92.73%   92.74%           
========================================
  Files          592      592           
  Lines        31289    31291    +2     
========================================
+ Hits         29015    29018    +3     
+ Misses        2274     2273    -1     

Files with missing lines	Coverage Δ
src/api/api.cpp	74.00% <100.00%> (+0.11%)	⬆️

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