Remove useless "return;" lines

Discussion: https://postgr.es/m/20191128144653.GA27883@alvherre.pgsql

src/interfaces/ecpg/compatlib/informix.c

@@ -529,7 +529,6 @@ void
 rtoday(date * d)
 {
 	PGTYPESdate_today(d);
-	return;
 }
 
 int
@@ -959,7 +958,6 @@ rupshift(char *str)
 	for (; *str != '\0'; str++)
 		if (islower((unsigned char) *str))
 			*str = toupper((unsigned char) *str);
-	return;
 }
 
 int

src/interfaces/ecpg/pgtypeslib/datetime.c

@@ -152,7 +152,6 @@ PGTYPESdate_today(date * d)
 	GetCurrentDateTime(&ts);
 	if (errno == 0)
 		*d = date2j(ts.tm_year, ts.tm_mon, ts.tm_mday) - date2j(2000, 1, 1);
-	return;
 }
 
 #define PGTYPES_DATE_NUM_MAX_DIGITS		20	/* should suffice for most

src/interfaces/ecpg/pgtypeslib/dt_common.c

@@ -624,8 +624,6 @@ j2date(int jd, int *year, int *month, int *day)
 	quad = julian * 2141 / 65536;
 	*day = julian - 7834 * quad / 256;
 	*month = (quad + 10) % 12 + 1;
-
-	return;
 }								/* j2date() */
 
 /* DecodeSpecial()

src/interfaces/ecpg/pgtypeslib/timestamp.c

@@ -297,7 +297,6 @@ PGTYPEStimestamp_current(timestamp * ts)
 	GetCurrentDateTime(&tm);
 	if (errno == 0)
 		tm2timestamp(&tm, 0, NULL, ts);
-	return;
 }
 
 static int

src/interfaces/libpq/fe-auth-scram.c

@@ -279,7 +279,6 @@ pg_fe_scram_exchange(void *opaq, char *input, int inputlen,
 error:
 	*done = true;
 	*success = false;
-	return;
 }
 
 /*