Ports: Switch to new ports system (#594)

Much redundancy is removed from package scripts with this system.
It also supports simple dependency management, uninstalling (through
BSD ports style plist files), cleaning up after itself (with clean,
clean_dist, clean_all commands), etc.

Ports/bash/patches/configure-system.patch

@@ -0,0 +1,13 @@
+diff --git a/support/config.sub b/support/config.sub
+index f208558e..fb8fa19e 100755
+--- a/support/config.sub
++++ b/support/config.sub
+@@ -1360,7 +1360,7 @@ case $os in
+ 	     | powermax* | dnix* | nx6 | nx7 | sei* | dragonfly* \
+ 	     | skyos* | haiku* | rdos* | toppers* | drops* | es* \
+ 	     | onefs* | tirtos* | phoenix* | fuchsia* | redox* | bme* \
+-	     | midnightbsd*)
++	     | midnightbsd* | serenity*)
+ 	# Remember, each alternative MUST END IN *, to match a version number.
+ 		;;
+ 	qnx*)

Ports/bash/patches/disable-locale.patch

@@ -0,0 +1,18 @@
+diff -Nru pristine/bash-5.0/locale.c bash-5.0/locale.c
++++ bash-5.0/locale.c	2019-05-21 02:18:05.843104487 +0200
+@@ -76,6 +76,7 @@
+ void
+ set_default_locale ()
+ {
++    return;
+ #if defined (HAVE_SETLOCALE)
+   default_locale = setlocale (LC_ALL, "");
+   if (default_locale)
+@@ -95,6 +96,7 @@
+ void
+ set_default_locale_vars ()
+ {
++    return;
+   char *val;
+ 
+#if defined (HAVE_SETLOCALE)

Ports/bash/patches/include-stdio.patch

@@ -0,0 +1,13 @@
+diff --git a/include/stdc.h b/include/stdc.h
+index c66492f0..5991f4bd 100644
+--- a/include/stdc.h
++++ b/include/stdc.h
+@@ -22,6 +22,8 @@
+ #if !defined (_STDC_H_)
+ #define _STDC_H_
+ 
++#include <stdio.h>
++
+ /* Adapted from BSD /usr/include/sys/cdefs.h. */
+ 
+ /* A function can be defined using prototypes and compile on both ANSI C