ecpg: Move function prototype into header file

PGTYPEStimestamp_defmt_scan() was declared twice inside different .c
files, with slightly different prototypes.  Move it into a header file
and correct the prototype.

src/interfaces/ecpg/pgtypeslib/dt.h

@@ -348,6 +348,10 @@ void		GetCurrentDateTime(struct tm *);
 int			date2j(int, int, int);
 void		TrimTrailingZeros(char *);
 void		dt2time(double, int *, int *, int *, fsec_t *);
+int			PGTYPEStimestamp_defmt_scan(char **str, char *fmt, timestamp * d,
+							int *year, int *month, int *day,
+							int *hour, int *minute, int *second,
+							int *tz);
 
 extern char *pgtypes_date_weekdays_short[];
 extern char *pgtypes_date_months[];

src/interfaces/ecpg/pgtypeslib/dt_common.c

@@ -2595,9 +2595,6 @@ pgtypes_defmt_scan(union un_fmt_comb * scan_val, int scan_type, char **pstr, cha
 }
 
 /* XXX range checking */
-int PGTYPEStimestamp_defmt_scan(char **, char *, timestamp *, int *, int *, int *,
-							int *, int *, int *, int *);
-
 int
 PGTYPEStimestamp_defmt_scan(char **str, char *fmt, timestamp * d,
 							int *year, int *month, int *day,

src/interfaces/ecpg/pgtypeslib/timestamp.c

@@ -18,9 +18,6 @@
 #include "pgtypes_date.h"
 
 
-int PGTYPEStimestamp_defmt_scan(char **, const char *, timestamp *, int *, int *, int *,
-							int *, int *, int *, int *);
-
 #ifdef HAVE_INT64_TIMESTAMP
 static int64
 time2t(const int hour, const int min, const int sec, const fsec_t fsec)