Make memory_error() a routine.

That makes the code more like Lemon as distributed.

Note that Lemon, as distributed, at least claims to have a bunch of
stuff "From the file "XXX.{c,h}", which might be the result of lemon.c
being an "amalgamation":

	https://www.sqlite.org/amalgamation.html

although, unlike SQLite, the individual bits of the amalgamation don't
appear to be present in the SQLite Fossil repository, so maybe they've
been permanently glued together.

Change-Id: I361d0d16be0744b127110d7d237fdd84e30b6432
Reviewed-on: https://code.wireshark.org/review/21105
Petri-Dish: Guy Harris <guy@alum.mit.edu>
Reviewed-by: Guy Harris <guy@alum.mit.edu>

tools/lemon/lemon.c

@@ -422,8 +422,8 @@ struct lemon {
 };
 
 #define MemoryCheck(X) if((X)==0){ \
-  fprintf(stderr,"Out of memory.  Aborting...\n"); \
-  exit(1); \
+  extern void memory_error(void); \
+  memory_error(); \
 }
 
 /**************** From the file "table.h" *********************************/
@@ -1513,6 +1513,14 @@ make_basename(char* fullname)
   return new_string;
 }
 
+/* Report an out-of-memory condition and abort.  This function
+** is used mostly by the "MemoryCheck" macro in struct.h
+*/
+void memory_error(void){
+  fprintf(stderr,"Out of memory.  Aborting...\n");
+  exit(1);
+}
+
 static int nDefine = 0;      /* Number of -D options on the command line */
 static char **azDefine = 0;  /* Name of the -D macros */