patch 8.2.1048: build failure without the eval feature

Problem:    Build failure without the eval feature.
Solution:   Add dummy typedef.

src/structs.h

@@ -1794,6 +1794,10 @@ typedef struct
 {
     int	    dummy;
 } scriptitem_T;
+typedef struct
+{
+    int	    dummy;
+} evalarg_T;
 #endif
 
 // Struct passed between functions dealing with function call execution.

src/version.c

@@ -754,6 +754,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1048,
 /**/
     1047,
 /**/