Ports: Make bash link again

No idea why this was suddenly broken, but removing these duplicated
declarations make it build to completion again.

Ports/bash/patches/remove-duplicate-declarations.patch

@@ -0,0 +1,21 @@
+--- bash-5.0/lib/readline/terminal.c.orig 2020-05-18 09:39:55.104000000 +0100
++++ bash-5.0/lib/readline/terminal.c 2020-05-18 09:40:42.409654415 +0100
+@@ -102,12 +102,12 @@
+
+ static int tcap_initialized;
+
+-#if !defined (__linux__) && !defined (NCURSES_VERSION)
+-# if defined (__EMX__) || defined (NEED_EXTERN_PC)
+-extern 
+-# endif /* __EMX__ || NEED_EXTERN_PC */
+-char PC, *BC, *UP;
+-#endif /* !__linux__ && !NCURSES_VERSION */
++// #if !defined (__linux__) && !defined (NCURSES_VERSION)
++// # if defined (__EMX__) || defined (NEED_EXTERN_PC)
++// extern 
++// # endif /* __EMX__ || NEED_EXTERN_PC */
++// char PC, *BC, *UP;
++// #endif /* !__linux__ && !NCURSES_VERSION */
+
+ /* Some strings to control terminal actions. These are output by tputs (). */
+ char *_rl_term_clreol;