patch 8.2.2307: a shell command in the vimrc causes terminal output

Problem:    A shell command in the vimrc causes terminal output.
Solution:   Do not call starttermcap() after a shell command if the termcap
            wasn't active before.

src/ex_cmds.c

@@ -1360,8 +1360,8 @@ do_shell(
 #endif
 #ifdef MSWIN
     int		winstart = FALSE;
-    int		keep_termcap = FALSE;
 #endif
+    int		keep_termcap = !termcap_active;
 
     /*
      * Disallow shell commands for "rvim".
@@ -1395,9 +1395,7 @@ do_shell(
     msg_putchar('\r');			// put cursor at start of line
     if (!autocmd_busy)
     {
-#ifdef MSWIN
 	if (!keep_termcap)
-#endif
 	    stoptermcap();
     }
 #ifdef MSWIN
@@ -1488,9 +1486,7 @@ do_shell(
 	}
 #endif // FEAT_GUI_MSWIN
 
-#ifdef MSWIN
 	if (!keep_termcap)	// if keep_termcap is TRUE didn't stop termcap
-#endif
 	    starttermcap();	// start termcap if not done by wait_return()
 
 	/*