Fix -Wliteral-suffix (#731886)

--- a/BasicExcel.cpp
+++ b/BasicExcel.cpp
@@ -4913,7 +4913,7 @@
 	do
 	{
 		char sname[50];
-		sprintf(sname, "Sheet"FMT_SIZE_T, sheetNo++);
+		sprintf(sname, "Sheet" FMT_SIZE_T, sheetNo++);
 		yesheet = AddWorksheet(sname, sheetIndex);
 	} while (!yesheet);
 	return yesheet;