Fix varargs stack repair.

Varargs-only stack repair (i.e. using #pragma optimize bit 3 but not bit 6) was broken by commit 32975b720f. It removed some code that was needed to allocate the direct page location used to hold the stack pointer value in that case. This would lead to invalid code being produced, which could cause a crash when run. The fix is to revert the erroneous parts of commit 32975b720f (which do not affect its core purpose of enabling intermediate code peephole optimization to be used when stack repair code is active).

CGI.pas

@@ -364,6 +364,7 @@ var
    symLength: integer;                  {length of debug symbol table}
    toolParms: boolean;                  {generate tool format parameters?}
    volatile: boolean;			{has a volatile qualifier been used?}
+   hasVarargsCall: boolean;             {does current function call any varargs fns?}
    
                                         {desk accessory variables}
                                         {------------------------}

Expression.pas

@@ -3508,6 +3508,8 @@ var
             Gen1tName(pc_cup, ord(hasVarargs and strictVararg),
                UsualUnaryConversions, fname);
             end; {else}
+         if hasVarargs then
+            hasVarargsCall := true;
 	 end {if}
       else
 	 GenTool(pc_tl1, ftype^.toolNum, long(ftype^.ftype^.size).lsw,

Gen.pas

@@ -7679,7 +7679,7 @@ while bk <> nil do begin
       end; {while}
    bk := bk^.next;
    end; {while}
-if saveStack or checkStack then begin
+if saveStack or checkStack or (strictVararg and hasVarargsCall) then begin
    stackLoc := minSize;
    minSize := minSize + 2;
    localSize := localSize + 2;

Parser.pas

@@ -4019,6 +4019,7 @@ if isFunction then begin
          end; {if}
       Gen2Name(dc_str, segType, 0, fName);
       doingMain := variable^.name^ = 'main';
+      hasVarargsCall := false;
       firstCompoundStatement := true;
       Gen0 (dc_pin);
       if not isAsm then