XGBoost: Fix type mismatch for CSR conversion in c_api

[yzhliu]

Description

There was a mismatch between bst_ulong in c_api.h and ctypes.c_size_t in python. If you run test_scipy_sparse in browser, it would trigger error like,

TypeError: Cannot convert 10 to a BigInt
    at ffi_call (pyodide.asm.js:10:189569)
    at pyodide.asm.wasm:0x276cba
    at pyodide.asm.wasm:0x270f9c
    at method_call_trampoline (pyodide.asm.js:10:218037)
    at pyodide.asm.wasm:0x126317
    at pyodide.asm.wasm:0x1e246f
    at pyodide.asm.wasm:0x1e00b3
    at pyodide.asm.wasm:0x1da6a5
    at pyodide.asm.wasm:0x126a07
    at pyodide.asm.wasm:0x1e248c
API.fatal_error @ pyodide.asm.js:10
pyodide.asm.js:10 Stack (most recent call first):
pyodide.asm.js:10   File "/lib/python3.10/site-packages/xgboost/data.py", line 87 in _from_scipy_csr
pyodide.asm.js:10   File "<ipython-input-9-f40ece33f18d>", line 1 in <module>
pyodide.asm.js:10   File "/lib/python3.10/site-packages/IPython/core/interactiveshell.py", line 3378 in run_code
...

In which 10 is the ncol.

I've also created an upstream PR dmlc/xgboost#8369

Checklists

• Add a CHANGELOG entry
• Add / update tests

[ryanking13]

Thanks a lot @yzhliu! It looks good to me. Let's wait for a review in your upstream PR. (Feel free to ping me when it's accepted)

[yzhliu]

Hi @ryanking13 thanks for the review. the upstream PR has been merged, I have also updated this PR per their suggestion. Let me if this is good to go.

[ryanking13]

Thanks a lot @yzhliu!