AIX: Update variable name which conflicts with system defined variable

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 349 matching lines @@
 V8_INLINE double __kernel_cos(double x, double y) {
   static const double
       one = 1.00000000000000000000e+00, /* 0x3FF00000, 0x00000000 */
       C1 = 4.16666666666666019037e-02,  /* 0x3FA55555, 0x5555554C */
       C2 = -1.38888888888741095749e-03, /* 0xBF56C16C, 0x16C15177 */
       C3 = 2.48015872894767294178e-05,  /* 0x3EFA01A0, 0x19CB1590 */
       C4 = -2.75573143513906633035e-07, /* 0xBE927E4F, 0x809C52AD */
       C5 = 2.08757232129817482790e-09,  /* 0x3E21EE9E, 0xBDB4B1C4 */
       C6 = -1.13596475577881948265e-11; /* 0xBDA8FAE9, 0xBE8838D4 */
 
-  double a, hz, z, r, qx;
+  double a, iz, z, r, qx;
   int32_t ix;
   GET_HIGH_WORD(ix, x);
   ix &= 0x7fffffff;                           /* ix = |x|'s high word*/
   if (ix < 0x3e400000) {                      /* if x < 2**27 */
     if (static_cast<int>(x) == 0) return one; /* generate inexact */
   }
   z = x * x;
   r = z * (C1 + z * (C2 + z * (C3 + z * (C4 + z * (C5 + z * C6)))));
   if (ix < 0x3FD33333) { /* if |x| < 0.3 */
     return one - (0.5 * z - (z * r - x * y));
   } else {
     if (ix > 0x3fe90000) { /* x > 0.78125 */
       qx = 0.28125;
     } else {
       INSERT_WORDS(qx, ix - 0x00200000, 0); /* x/4 */
     }
-    hz = 0.5 * z - qx;
+    iz = 0.5 * z - qx;
     a = one - qx;
-    return a - (hz - (z * r - x * y));
+    return a - (iz - (z * r - x * y));
   }
 }
 
 /* __kernel_rem_pio2(x,y,e0,nx,prec,ipio2)
  * double x[],y[]; int e0,nx,prec; int ipio2[];
  *
  * __kernel_rem_pio2 return the last three digits of N with
  *              y = x - N*pi/2
  * so that |y| < pi/2.
  *
@@ skipping 1904 matching lines @@
     /* argument reduction needed */
     n = __ieee754_rem_pio2(x, y);
     /* 1 -> n even, -1 -> n odd */
     return __kernel_tan(y[0], y[1], 1 - ((n & 1) << 1));
   }
 }
 
 }  // namespace ieee754
 }  // namespace base
 }  // namespace v8