Merge pull request #327 from toughengineer/int_multiplication_by_power_of_10

Minor fix of forward declaration

Author: lemire

include/fast_float/fast_float.h

@@ -60,10 +60,8 @@ from_chars_advanced(UC const *first, UC const *last, T &value,
  */
 FASTFLOAT_CONSTEXPR20 inline double
 integer_times_pow10(uint64_t mantissa, int decimal_exponent) noexcept;
-FASTFLOAT_CONSTEXPR20 inline
-    typename std::enable_if<is_supported_float_type<double>::value,
-                            double>::type
-    integer_times_pow10(int64_t mantissa, int decimal_exponent) noexcept;
+FASTFLOAT_CONSTEXPR20 inline double
+integer_times_pow10(int64_t mantissa, int decimal_exponent) noexcept;
 
 /**
  * from_chars for integer types.