fix(main/mpc): use termux's mpd socket if --host is not given

Previously mpc had to be run with '--host $PREFIX/var/run/mpd.socket',
or else we got:

  MPD error: Connection refused

Patch mpd to use our socket if --host option is omitted, so that it
works without extra options.

packages/mpc/build.sh

@@ -3,7 +3,7 @@ TERMUX_PKG_DESCRIPTION="Minimalist command line interface for MPD"
 TERMUX_PKG_LICENSE="GPL-2.0"
 TERMUX_PKG_MAINTAINER="@termux"
 TERMUX_PKG_VERSION=0.34
-TERMUX_PKG_REVISION=1
+TERMUX_PKG_REVISION=2
 TERMUX_PKG_SRCURL=https://www.musicpd.org/download/mpc/${TERMUX_PKG_VERSION:0:1}/mpc-$TERMUX_PKG_VERSION.tar.xz
 TERMUX_PKG_SHA256=691e3f3654bc10d022bb0310234d0bc2d8c075a698f09924d9ebed8f506fda20
 TERMUX_PKG_DEPENDS="libiconv, libmpdclient"

packages/mpc/src-options.c.patch

@@ -0,0 +1,15 @@
+--- ../options.c.orig	2022-07-28 21:21:13.150375029 +0200
++++ ./src/options.c	2022-07-28 21:25:59.500403799 +0200
+@@ -304,7 +304,11 @@
+ 		option_error(ERROR_MISSING_ARGUMENT, opt->longopt, opt->argument);
+ 
+ 	/* Parse the password from the host */
+-	if (options.host != NULL &&
++	if (options.host == NULL) {
++		/* Use socket in @TERMUX_$PREFIX@/var/run/mpd.socket
++		   if none was specified */
++		options.host = "@TERMUX_PREFIX@/var/run/mpd.socket";
++	} else if (options.host != NULL &&
+ 	    (tmp = strchr(options.host, '@')) != NULL &&
+ 	    /* if the host begins with a '@' then it's not an empty
+ 	       password but an abstract socket */