bench: fix overflow

Previously, scaling by `alpha` in single-precision could quickly
lead to infinities, resulting in subsequent `NaN` calculations.

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type: pre_commit_static_analysis_report
description: Results of running static analysis checks when committing changes.
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---

Author: kgryte

lib/node_modules/@stdlib/blas/base/cscal/benchmark/fortran/benchmark.length.f

@@ -152,7 +152,7 @@ end subroutine cscal
     ! ..
     call random_number( r1 )
     call random_number( r2 )
-    alpha = cmplx( (real(r1)*5.0), (real(r2)*5.0) )
+    alpha = cmplx( (real(r1)*0.5), (real(r2)*0.5) )
     do i = 1, len
       call random_number( r1 )
       call random_number( r2 )