vim-patch:8.2.1909: number of status line items is limited to 80

Problem:    Number of status line items is limited to 80.
Solution:   Dynamically allocate the arrays. (Rom Grk, closes vim/vim#7181)
8133cc6bf4

The members of stl_item_T have not been prefixed with stl_ contrary to
the vim patch because the amount of stl_ prefixes on single lines of
code in that region was hurtful to readability.

src/nvim/buffer_defs.h

@@ -361,14 +361,36 @@ struct mapblock {
   sctx_T m_script_ctx;          // SCTX where map was defined
 };
 
-/*
- * Used for highlighting in the status line.
- */
+/// Used for highlighting in the status line.
+typedef struct stl_hlrec stl_hlrec_t;
 struct stl_hlrec {
   char_u      *start;
   int userhl;                   // 0: no HL, 1-9: User HL, < 0 for syn ID
 };
 
+/// Used for building the status line.
+typedef struct stl_item stl_item_t;
+struct stl_item {
+  // Where the item starts in the status line output buffer
+  char_u *start;
+  // Function to run for ClickFunc items.
+  char *cmd;
+  // The minimum width of the item
+  int minwid;
+  // The maximum width of the item
+  int maxwid;
+  enum {
+    Normal,
+    Empty,
+    Group,
+    Separate,
+    Highlight,
+    TabPage,
+    ClickFunc,
+    Trunc
+  } type;
+};
+
 // values for b_syn_spell: what to do with toplevel text
 #define SYNSPL_DEFAULT  0       // spell check if @Spell not defined
 #define SYNSPL_TOP      1       // spell check toplevel text