Fix C lint errors

[stdlib-bot]

C Linting Failures

Linting failures were detected in the automated lint workflow run.

Workflow Details

• Run: https://github.com/stdlib-js/stdlib/actions/runs/16254855087
• Type: C Linting
• Date: 2025-07-14 00:15:12 UTC

Error Details

lib/node_modules/@stdlib/blas/ext/base/dnansumkbn2/benchmark/c/benchmark.length.c:114:40: warning: Uninitialized variable: x [uninitvar]
  v = stdlib_strided_dnansumkbn2( len, x, 1 );
                                       ^
--
                                       ^
lib/node_modules/@stdlib/blas/ext/base/dnansumkbn2/benchmark/c/benchmark.length.c:151:48: warning: Uninitialized variable: x [uninitvar]
  v = stdlib_strided_dnansumkbn2_ndarray( len, x, 1, 0 );
                                               ^

Pull Request Instructions

• Please use the following PR title format:
  "chore: fix C lint errors (issue #<ISSUE_NUMBER>)".
• Reference this issue in the "Related Issues" section of the PR body as "resolves #<ISSUE_NUMBER>".