comctl32: void functions should not return a value

[Andrew Talbot]

Changelog:
    comctl32: void functions should not return a value.

diff --git a/dlls/comctl32/monthcal.c b/dlls/comctl32/monthcal.c
index 27d2cf0..2ad4812 100644
--- a/dlls/comctl32/monthcal.c
+++ b/dlls/comctl32/monthcal.c
@@ -481,13 +481,13 @@ static inline void MONTHCAL_GetMonth(SYSTEMTIME *date, INT months)
 /* properly updates date to point on next month */
 static inline void MONTHCAL_GetNextMonth(SYSTEMTIME *date)
 {
-  return MONTHCAL_GetMonth(date, 1);
+  MONTHCAL_GetMonth(date, 1);
 }
 
 /* properly updates date to point on prev month */
 static inline void MONTHCAL_GetPrevMonth(SYSTEMTIME *date)
 {
-  return MONTHCAL_GetMonth(date, -1);
+  MONTHCAL_GetMonth(date, -1);
 }
 
 /* Returns full date for a first currently visible day */