patch 8.2.0124: compiler warnings for variable types

Problem:    Compiler warnings for variable types.
Solution:   Change type, add type cast. (Mike Williams)
diff --git a/src/memline.c b/src/memline.c
index 2ac47af..2c41539 100644
--- a/src/memline.c
+++ b/src/memline.c
@@ -5753,8 +5753,8 @@
 	else
 	{
 #ifdef FEAT_PROP_POPUP
-	    long textprop_total = 0;
-	    long textprop_size = 0;
+	    size_t textprop_total = 0;
+	    size_t textprop_size = 0;
 	    char_u *l1, *l2;
 #endif
 
@@ -5774,7 +5774,7 @@
 		if (!(offset >= size
 			+ text_end - (int)((dp->db_index[idx]) & DB_INDEX_MASK)
 #ifdef FEAT_PROP_POPUP
-			- textprop_total - textprop_size
+			- (long)(textprop_total - textprop_size)
 #endif
 			+ ffdos))
 		    break;