Fix arm build of malloc_stats_print

[CalvinNeo]

What is changed and how it works?

Issue Number: Close #xxx

What's Changed:

There is a error on arm build

error[E0308]: mismatched types
   --> proxy_components/proxy_ffi/src/jemalloc_utils.rs:186:26
    |
186 |                     Some(write_to_string),
    |                     ---- ^^^^^^^^^^^^^^^ expected fn pointer, found fn item
    |                     |
    |                     arguments to this enum variant are incorrect
    |
    = note: expected fn pointer `unsafe extern "C" fn(_, *const i8)`
                  found fn item `extern "C" fn(_, *const u8) {write_to_string}`
help: the type constructed contains `extern "C" fn(*mut c_void, *const u8) {write_to_string}` due to the type of the argument passed
   --> proxy_components/proxy_ffi/src/jemalloc_utils.rs:186:21
    |
186 |                     Some(write_to_string),
    |                     ^^^^^---------------^
    |                          |
    |                          this argument influences the type of `Some`
note: tuple variant defined here
   --> /root/.rustup/toolchains/nightly-2023-12-28-aarch64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/option.rs:578:5
    |
578 |     Some(#[stable(feature = "rust1", since = "1.0.0")] T),
    |     ^^^^

error[E0308]: mismatched types
   --> proxy_components/proxy_ffi/src/jemalloc_utils.rs:188:21
    |
185 |                 malloc_stats_print(
    |                 ------------------ arguments to this function are incorrect
...
188 |                     ops_str,
    |                     ^^^^^^^ expected `*const i8`, found `*const u8`
    |
    = note: expected raw pointer `*const i8`
               found raw pointer `*const u8`
note: function defined here
   --> proxy_components/proxy_ffi/src/jemalloc_utils.rs:23:12
    |
23  |     pub fn malloc_stats_print(
    |            ^^^^^^^^^^^^^^^^^^

The fix is to use c_char instead of u8 or i8.

Related changes

• PR to update pingcap/docs/pingcap/docs-cn:
• Need to cherry-pick to the release branch

Check List

Tests

• Unit test
• Integration test
• Manual test (add detailed scripts or steps below)
• No code

Side effects

• Performance regression: Consumes more CPU
• Performance regression: Consumes more Memory
• Breaking backward compatibility

Release note

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: JaySon-Huang

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• HACKED_OWNERS [JaySon-Huang]

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[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2024-12-17 08:44:10.292197442 +0000 UTC m=+946440.380999981: ☑️ agreed by JaySon-Huang.