fix: Rename template parameter BLOCK_SIZE to avoid macro conflict

[tanghaoth90]

The template parameter BLOCK_SIZE used in internal/arch/common/unicode_common.h conflicts with a common macro of the same name defined in system headers like <linux/fs.h> (on Linux/Android). This causes compilation errors when <sonic/sonic.h> is included after such headers.

This pull request renames the template parameter to prevent this macro pollution, improving the library's robustness and compatibility in various build environments.

Changes

• Renamed the template parameter BLOCK_SIZE in internal/arch/common/unicode_common.h.
• Updated all internal usages of this template parameter to reflect the new name.

Reproduce

The fix has been verified by building the following minimal reproducible example, which now compiles successfully:

// g++ -I./include -mpclmul -march=haswell --std=c++11 -O3 thisfile.cpp
#include <linux/fs.h>
#include <sonic/sonic.h>

int main() {
    return 0;
}

The compilation error message is shown below:

.../include/sonic/internal/arch/neon/../common/unicode_common.h:271:18: error: expected ')'
.../sdk/ndk/21.1.6352462/toolchains/llvm/prebuilt/darwin-x86_64/sysroot/usr/include/linux/fs.h:29:21: note: expanded from macro 'BLOCK_SIZE'
.../include/sonic/internal/arch/neon/../common/unicode_common.h:271:18: note: to match this '('
.../sdk/ndk/21.1.6352462/toolchains/llvm/prebuilt/darwin-x86_64/sysroot/usr/include/linux/fs.h:29:20: note: expanded from macro 'BLOCK_SIZE'

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 76.04%. Comparing base (4250a05) to head (04e6acc).
⚠️ Report is 19 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #127      +/-   ##
==========================================
+ Coverage   74.79%   76.04%   +1.25%     
==========================================
  Files          21       22       +1     
  Lines        2436     2680     +244     
  Branches      667      750      +83     
==========================================
+ Hits         1822     2038     +216     
+ Misses        297      106     -191     
- Partials      317      536     +219     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.