Use std:: on symbols declared in C++-style C headers.

src/conversions.cc

Index: src/conversions.cc
diff --git a/src/conversions.cc b/src/conversions.cc
index 397f3c57fb8628de2e39b521ff2298dcf977db41..9c52d41e5d3f42bc0deda9ac1ebd70059da1f00a 100644
--- a/src/conversions.cc
+++ b/src/conversions.cc
@@ -394,14 +394,14 @@ char* DoubleToRadixCString(double value, int radix) {
   if (is_negative) value = -value;
 
   // Get the integer part and the decimal part.
-  double integer_part = floor(value);
+  double integer_part = std::floor(value);
   double decimal_part = value - integer_part;
 
   // Convert the integer part starting from the back.  Always generate
   // at least one digit.
   int integer_pos = kBufferSize - 2;
   do {
-    double remainder = fmod(integer_part, radix);
+    double remainder = std::fmod(integer_part, radix);
     integer_buffer[integer_pos--] = chars[static_cast<int>(remainder)];
     integer_part -= remainder;
     integer_part /= radix;
@@ -424,8 +424,8 @@ char* DoubleToRadixCString(double value, int radix) {
   while ((decimal_part > 0.0) && (decimal_pos < kBufferSize - 1)) {
     decimal_part *= radix;
     decimal_buffer[decimal_pos++] =
-        chars[static_cast<int>(floor(decimal_part))];
-    decimal_part -= floor(decimal_part);
+        chars[static_cast<int>(std::floor(decimal_part))];
+    decimal_part -= std::floor(decimal_part);
   }
   decimal_buffer[decimal_pos] = '\0';