-Wuninitialized fixes

base/third_party/dmg_fp/dtoa.cc

 /****************************************************************
  *
  * The author of this software is David M. Gay.
  *
  * Copyright (c) 1991, 2000, 2001 by Lucent Technologies.
  *
  * Permission to use, copy, modify, and distribute this software for any
  * purpose without fee is hereby granted, provided that this entire notice
  * is included in all copies of any software which is or includes a copy
  * or modification of this software and in all copies of the supporting
@@ skipping 3551 matching lines @@
         */
 
         int bbits, b2, b5, be, dig, i, ieps, ilim, ilim0, ilim1,
                 j, j1, k, k0, k_check, leftright, m2, m5, s2, s5,
                 spec_case, try_quick;
         Long L;
 #ifndef Sudden_Underflow
         int denorm;
         ULong x;
 #endif
-        Bigint *b, *b1, *delta, *mlo, *mhi, *S;
+        Bigint *b, *b1, *delta, *mlo = 0, *mhi, *S;  // clang (no idea if correct)
         U d2, eps, u;
         double ds;
         char *s, *s0;
 #ifdef SET_INEXACT
         int inexact, oldinexact;
 #endif
 #ifdef Honor_FLT_ROUNDS /*{*/
         int Rounding;
 #ifdef Trust_FLT_ROUNDS /*{{ only define this if FLT_ROUNDS really works! */
         Rounding = Flt_Rounds;
@@ skipping 617 matching lines @@
 #endif
         Bfree(b);
         *s = 0;
         *decpt = k + 1;
         if (rve)
                 *rve = s;
         return s0;
         }
 
 }  // namespace dmg_fp