Export numeric interface to public (#392)

CBDB not allow building pg numeric from other formats. Numeric objects can only be constructed from string, which
means that the caller needs to convert its own data into a specific format string, then convert the string into numeric. 
This is a very inefficient method.

In order to better convert data of other structures into pg numeric, The current changes will expose the main structures
and methods defined in numeric.c to numeric.h

Author: jiaqizho

contrib/btree_gist/btree_numeric.c

@@ -186,9 +186,9 @@ gbt_numeric_penalty(PG_FUNCTION_ARGS)
 											 NumericGetDatum(us),
 											 NumericGetDatum(os)));
 
-	if (numeric_is_nan(us))
+	if (NUMERIC_IS_NAN(us))
 	{
-		if (numeric_is_nan(os))
+		if (NUMERIC_IS_NAN(os))
 			*result = 0.0;
 		else
 			*result = 1.0;

contrib/jsonb_plpython/jsonb_plpython.c

@@ -390,11 +390,11 @@ PLyNumber_ToJsonbValue(PyObject *obj, JsonbValue *jbvNum)
 	 * jsonb doesn't allow NaN or infinity (per JSON specification), so we
 	 * have to reject those here explicitly.
 	 */
-	if (numeric_is_nan(num))
+	if (NUMERIC_IS_NAN(num))
 		ereport(ERROR,
 				(errcode(ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE),
 				 errmsg("cannot convert NaN to jsonb")));
-	if (numeric_is_inf(num))
+	if (NUMERIC_IS_INF(num))
 		ereport(ERROR,
 				(errcode(ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE),
 				 errmsg("cannot convert infinity to jsonb")));

src/backend/cdb/cdblegacyhash.c

@@ -377,7 +377,7 @@ cdblegacyhash_numeric(PG_FUNCTION_ARGS)
 	size_t		len;		/* length for the data buffer */
 	uint32		hash;
 
-	if (numeric_is_nan(num))
+	if (NUMERIC_IS_NAN(num))
 	{
 		static const uint32 nanbuf = NAN_VAL;
 
@@ -387,8 +387,8 @@ cdblegacyhash_numeric(PG_FUNCTION_ARGS)
 	else
 		/* not a nan */
 	{
-		buf = numeric_digits(num);
-		len = numeric_len(num);
+		buf = NUMERIC_DIGITS(num);
+		len = NUMERIC_NDIGITS(num) * sizeof(NumericDigit);
 	}
 
 	/* do the hash using the selected algorithm */

src/backend/gpopt/gpdbwrappers.cpp

@@ -1717,7 +1717,7 @@ gpdb::NumericIsNan(Numeric num)
 {
 	GP_WRAP_START;
 	{
-		return numeric_is_nan(num);
+		return NUMERIC_IS_NAN(num);
 	}
 	GP_WRAP_END;
 	return false;

src/backend/utils/adt/complex_type.c

@@ -1313,7 +1313,7 @@ numeric2complex(PG_FUNCTION_ARGS)
 	Numeric		num = PG_GETARG_NUMERIC(0);
 	double		float_num;
 
-	if (numeric_is_nan(num))
+	if (NUMERIC_IS_NAN(num))
 	{
 		float_num = get_float8_nan();
 	}