Fix arm compilation. DiyFp multiplications are now in a separate procedure.

src/diy_fp.h

Index: src/diy_fp.h
===================================================================
--- src/diy_fp.h	(revision 4162)
+++ src/diy_fp.h	(working copy)
@@ -64,26 +64,7 @@
 
 
   // this = this * other.
-  void Multiply(const DiyFp& other) {
-    // Simply "emulates" a 128 bit multiplication.
-    // However: the resulting number only contains 64 bits. The least
-    // significant 64 bits are only used for rounding the most significant 64
-    // bits.
-    const uint64_t kM32 = 0xFFFFFFFFu;
-    uint64_t a = f_ >> 32;
-    uint64_t b = f_ & kM32;
-    uint64_t c = other.f_ >> 32;
-    uint64_t d = other.f_ & kM32;
-    uint64_t ac = a * c;
-    uint64_t bc = b * c;
-    uint64_t ad = a * d;
-    uint64_t bd = b * d;
-    uint64_t tmp = (bd >> 32) + (ad & kM32) + (bc & kM32);
-    tmp += 1U << 31;  // round
-    uint64_t result_f = ac + (ad >> 32) + (bc >> 32) + (tmp >> 32);
-    e_ += other.e_ + 64;
-    f_ = result_f;
-  }
+  void Multiply(const DiyFp& other);
 
   // returns a * b;
   static DiyFp Times(const DiyFp& a, const DiyFp& b) {