Fixes 'multiple definition errors' when building with GCC 10+

From: https://bugs.gentoo.org/710796
Originally from: https://gitlab.freedesktop.org/pipewire/pipewire/-/commit/a62e41e
and https://gitlab.freedesktop.org/pipewire/pipewire/-/commit/7a976c7

--- a/spa/plugins/bluez5/a2dp-codecs.h
+++ b/spa/plugins/bluez5/a2dp-codecs.h
@@ -284,15 +284,15 @@
         }
 }
 
-const a2dp_sbc_t bluez_a2dp_sbc;
+extern const a2dp_sbc_t bluez_a2dp_sbc;
 #if ENABLE_MP3
-const a2dp_mpeg_t bluez_a2dp_mpeg;
+extern const a2dp_mpeg_t bluez_a2dp_mpeg;
 #endif
 #if ENABLE_AAC
-const a2dp_aac_t bluez_a2dp_aac;
+extern const a2dp_aac_t bluez_a2dp_aac;
 #endif
 #if ENABLE_APTX
-const a2dp_aptx_t bluez_a2dp_aptx;
+extern const a2dp_aptx_t bluez_a2dp_aptx;
 #endif
 
 #endif
--- a/spa/plugins/bluez5/bluez5-monitor.c
+++ b/spa/plugins/bluez5/bluez5-monitor.c
@@ -75,7 +75,7 @@
 	struct spa_list transport_list;
 };
 
-struct spa_handle_factory spa_a2dp_sink_factory;
+extern struct spa_handle_factory spa_a2dp_sink_factory;
 
 static void fill_item(struct spa_bt_monitor *this, struct spa_bt_transport *transport,
 		struct spa_pod **result, struct spa_pod_builder *builder)
--- a/spa/plugins/bluez5/meson.build
+++ b/spa/plugins/bluez5/meson.build
@@ -1,7 +1,8 @@
 
 bluez5_sources = ['plugin.c',
 		  'a2dp-sink.c',
-                  'bluez5-monitor.c']
+		  'a2dp-codecs.c',
+		  'bluez5-monitor.c']
 
 bluez5lib = shared_library('spa-bluez5',
 	bluez5_sources,
42837c449e55b91fae14fa17'>diff</a></td><td class='form'><form class='right' method='get' action='/guix/log/tests/profiles.scm'>
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<div class='path'>path: <a href='/guix/log/?id=3e968af4726192b042837c449e55b91fae14fa17'>root</a>/<a href='/guix/log/tests?id=3e968af4726192b042837c449e55b91fae14fa17'>tests</a>/<a href='/guix/log/tests/profiles.scm?id=3e968af4726192b042837c449e55b91fae14fa17'>profiles.scm</a></div><div class='content'><table class='list nowrap'><tr class='nohover'><th class='left'>Age</th><th class='left'>Commit message (<a href='/guix/log/tests/profiles.scm?id=3e968af4726192b042837c449e55b91fae14fa17&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2023-10-28 00:17:24 +0200'>2023-10-28</span></td><td><a href='/guix/commit/tests/profiles.scm?id=344e39c928bdb8e6b7e5ac79d94535921a414a05'>profiles: Hooks honor the #:system parameter of ‘profile-derivation’.</a><span class='msg-avail'>...<span class='msg-tooltip'>Fixes &lt;https://issues.guix.gnu.org/65225&gt;.

* guix/profiles.scm (info-dir-file, package-cache-file)
(info-dir-file, ghc-package-cache-file, ca-certificate-bundle)
(emacs-subdirs, gdk-pixbuf-loaders-cache-file, glib-schemas)
(gtk-icon-themes, gtk-im-modules, linux-module-database)
(xdg-desktop-database, xdg-mime-database, fonts-dir-file)
(manual-database, manual-database/optional): Add optional #:system
parameter and pass it to ‘gexp-&gt;derivation’.
(profile-derivation): Pass HOOK a second parameter, SYSTEM.
* gnu/bootloader.scm (efi-bootloader-profile)[efi-bootloader-profile-hook]:
Add optional #:system parameter and pass it to ‘gexp-&gt;derivation’.
* guix/channels.scm (package-cache-file): Likewise.
* tests/profiles.scm ("profile-derivation, #:system, and hooks"): New
test.

Reported-by: Tobias Geerinckx-Rice &lt;me@tobias.gr&gt;
</span></span></td><td>Ludovic Courtès</td></tr>