message: Use buffer with a static size in convert_number_to_mantissa_exponent
  We use references to arrays elsewhere in the codebase and there's just
  one caller for this function so it's easier to fix the size.
  This will simplify snprintf refactoring.
diff: @@ -7998,11 +7998,11 @@ PUGI__NS_BEGIN
  // gets mantissa digits in the form of 0.xxxxx with 0. implied and the exponent
  #if defined(PUGI__MSVC_CRT_VERSION) && PUGI__MSVC_CRT_VERSION >= 1400 && !defined(_WIN32_WCE)
  - PUGI__FN void convert_number_to_mantissa_exponent(double value, char* buffer, size_t buffer_size, char** out_mantissa, int* out_exponent)
  + PUGI__FN void convert_number_to_mantissa_exponent(double value, char (&buffer)[32], char** out_mantissa, int* out_exponent)
  {
  // get base values
  int sign, exponent;
  - _ecvt_s(buffer, buffer_size, value, DBL_DIG + 1, &exponent, &sign);
  + _ecvt_s(buffer, sizeof(buffer), value, DBL_DIG + 1, &exponent, &sign);
  // truncate redundant zeros
  truncate_zeros(buffer, buffer + strlen(buffer));
  @@ -8012,20 +8012,18 @@ PUGI__NS_BEGIN
  *out_exponent = exponent;
  }
  #else
  - PUGI__FN void convert_number_to_mantissa_exponent(double value, char* buffer, size_t buffer_size, char** out_mantissa, int* out_exponent)
  + PUGI__FN void convert_number_to_mantissa_exponent(double value, char (&buffer)[32], char** out_mantissa, int* out_exponent)
  {
  // get a scientific notation value with IEEE DBL_DIG decimals
  #if defined(PUGI__HAVE_SNPRINTF)
  - snprintf(buffer, buffer_size, "%.*e", DBL_DIG, value);
  + snprintf(buffer, 32, "%.*e", DBL_DIG, value);
  #elif defined(PUGI__MSVC_CRT_VERSION)
  - _snprintf(buffer, buffer_size, "%.*e", DBL_DIG, value);
  - buffer[buffer_size - 1] = '\0';
  + _snprintf(buffer, 32, "%.*e", DBL_DIG, value);
  + buffer[31] = '\0';
  #else
  sprintf(buffer, "%.*e", DBL_DIG, value);
  - assert(strlen(buffer) < buffer_size);
  #endif
  -
  // get the exponent (possibly negative)
  char* exponent_string = strchr(buffer, 'e');
  assert(exponent_string);
  @@ -8061,7 +8059,7 @@ PUGI__NS_BEGIN
  char* mantissa;
  int exponent;
  - convert_number_to_mantissa_exponent(value, mantissa_buffer, sizeof(mantissa_buffer), &mantissa, &exponent);
  + convert_number_to_mantissa_exponent(value, mantissa_buffer, &mantissa, &exponent);
  // allocate a buffer of suitable length for the number
  size_t result_size = strlen(mantissa_buffer) + (exponent > 0 ? exponent : -exponent) + 4;
  