Fix compilation error on gcc 4.8.5 on s390x

src/base/ieee754.cc

 // The following is adapted from fdlibm (http://www.netlib.org/fdlibm).
 //
 // ====================================================
 // Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
 //
 // Developed at SunSoft, a Sun Microsystems, Inc. business.
 // Permission to use, copy, modify, and distribute this
 // software is freely granted, provided that this notice
 // is preserved.
 // ====================================================
@@ skipping 591 matching lines @@
       z = one - z;
       if (carry != 0) z -= scalbn(one, q0);
     }
   }
 
   /* check if recomputation is needed */
   if (z == zero) {
     j = 0;
     for (i = jz - 1; i >= jk; i--) j |= iq[i];
     if (j == 0) { /* need recomputation */
-      for (k = 1; iq[jk - k] == 0; k++) {
+      for (k = 1; jk >= k && iq[jk - k] == 0; k++) {
         /* k = no. of terms needed */
       }
 
       for (i = jz + 1; i <= jz + k; i++) { /* add q[jz+1] to q[jz+k] */
         f[jx + i] = ipio2[jv + i];
         for (j = 0, fw = 0.0; j <= jx; j++) fw += x[j] * f[jx + i - j];
         q[i] = fw;
       }
       jz += k;
       goto recompute;
@@ skipping 2114 matching lines @@
     /* |x| >= 22, return +-1 */
   } else {
     z = one - tiny; /* raise inexact flag */
   }
   return (jx >= 0) ? z : -z;
 }
 
 }  // namespace ieee754
 }  // namespace base
 }  // namespace v8