Fix a problem where zero-initializing a one-byte array would crash the system.

Also, generate better code for zero-initializing small arrays.

The problem was that the code would call the library routine ~ZERO with a size of 1, but it only works properly with a size of 2 or more. While adding a check here, I also changed it to not call ~ZERO for other small arrays (<=10 bytes), since it is generally more efficient to just initialize them directly.

The initializations in the following are examples that could trigger the problem:

int main(void)
{
    struct { int i; char s[1]; } foo = {1, 0};
    char arr[2][1] = {2};
}

Parser.pas

@@ -3662,7 +3662,9 @@ procedure DoStatement;
                   with iPtr^.itree^ do
         	     if token.kind = intconst then
                         if token.ival = 0 then
-                           ZeroFill := true;
+                                        {don't call ~ZERO for very small arrays}
+                           if elements * itype^.size > 10 then
+                              ZeroFill := true;
          end; {ZeroFill}