disable the fast path for inc=1, alpha=0 as it does not handle x=NaN or Inf

kernel/mips/sscal_msa.c

@@ -42,7 +42,7 @@ int CNAME(BLASLONG n, BLASLONG dummy0, BLASLONG dummy1, FLOAT da, FLOAT *x,
 
     if (1 == inc_x)
     {
-        if (0.0 == da)
+        if (0) // if (0.0 == da)
         {
             v4f32 zero_v = {0.0, 0.0, 0.0, 0.0};
 
@@ -259,7 +259,10 @@ int CNAME(BLASLONG n, BLASLONG dummy0, BLASLONG dummy1, FLOAT da, FLOAT *x,
         {
             for (i = n; i--;)
             {
-                *x = 0;
+                if (isfinite(*x)
+                          *x = 0;
+                else
+                          *x = NAN;
                 x += inc_x;
             }
         }