patch 8.2.3375: using uninitialized memory

Problem:    Using uninitialized memory.
Solution:   Initialize textprop_save_len.
diff --git a/src/memline.c b/src/memline.c
index 2192036..9fc689f 100644
--- a/src/memline.c
+++ b/src/memline.c
@@ -289,6 +289,7 @@
     buf->b_ml.ml_line_lnum = 0;	// no cached line
 #ifdef FEAT_BYTEOFF
     buf->b_ml.ml_chunksize = NULL;
+    buf->b_ml.ml_usedchunks = 0;
 #endif
 
     if (cmdmod.cmod_flags & CMOD_NOSWAPFILE)
@@ -3607,7 +3608,7 @@
     int		ret = FAIL;
 #ifdef FEAT_PROP_POPUP
     char_u	*textprop_save = NULL;
-    int		textprop_save_len;
+    int		textprop_save_len = 0;
 #endif
 
     if (lowest_marked && lowest_marked > lnum)