patch 8.2.0378: prop_find() does not find all props

Problem:    prop_find() does not find all props.
Solution:   Check being in the start line. (Axel Forsman, closes #5776)

src/testdir/test_textprop.vim

@@ -213,6 +213,17 @@ func Test_prop_find()
   call prop_type_delete('prop_name')
 endfunc
 
+func Test_prop_find_smaller_len_than_match_col()
+  new
+  call prop_type_add('test', {'highlight': 'ErrorMsg'})
+  call setline(1, ['xxxx', 'x'])
+  call prop_add(1, 4, {'type': 'test'})
+  call assert_equal({'id': 0, 'lnum': 1, 'col': 4, 'type': 'test', 'length': 0, 'start': 1, 'end': 1},
+        \ prop_find({'type': 'test', 'lnum': 2, 'col': 1}, 'b'))
+  bwipe!
+  call prop_type_delete('test')
+endfunc
+
 func Test_prop_add()
   new
   call AddPropTypes()

src/textprop.c

@@ -663,6 +663,7 @@ f_prop_find(typval_T *argvars, typval_T *rettv)
 	    mch_memmove(&prop, text + textlen + i * sizeof(textprop_T),
 			    sizeof(textprop_T));
 
+	    if (lnum == lnum_start)
 		if (dir < 0)
 		{
 		    if (col < prop.tp_col)

src/version.c

@@ -738,6 +738,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    378,
 /**/
     377,
 /**/