The custom mutex definition in Seq24 clashes with the mutex defined in gtkmm.
This patch renames the custom definition.

See https://bugs.launchpad.net/seq24/+bug/1647614 for upstream bug report.

diff --git a/src/midibus.h b/src/midibus.h
index 2cdf8e8..1bb02bd 100644
--- a/src/midibus.h
+++ b/src/midibus.h
@@ -90,7 +90,7 @@ class midibus
 
 
     /* locking */
-    mutex m_mutex;
+    seq24mutex m_mutex;
 
     /* mutex */
     void lock();
@@ -208,7 +208,7 @@ class mastermidibus
     sequence *m_seq;
 
     /* locking */
-    mutex m_mutex;
+    seq24mutex m_mutex;
 
     /* mutex */
     void lock();
diff --git a/src/midibus_portmidi.h b/src/midibus_portmidi.h
index 0119e9c..8c6a27a 100644
--- a/src/midibus_portmidi.h
+++ b/src/midibus_portmidi.h
@@ -65,7 +65,7 @@ class midibus
     long m_lasttick;
 
     /* locking */
-    mutex m_mutex;
+    seq24mutex m_mutex;
 
     /* mutex */
     void lock();
@@ -164,7 +164,7 @@ class mastermidibus
     sequence *m_seq;
 
     /* locking */
-    mutex m_mutex;
+    seq24mutex m_mutex;
 
     /* mutex */
     void lock();
diff --git a/src/mutex.cpp b/src/mutex.cpp
index b3f23fd..914114f 100644
--- a/src/mutex.cpp
+++ b/src/mutex.cpp
@@ -20,23 +20,23 @@
 
 #include "mutex.h"
 
-const pthread_mutex_t mutex::recmutex = PTHREAD_RECURSIVE_MUTEX_INITIALIZER_NP;
+const pthread_mutex_t seq24mutex::recmutex = PTHREAD_RECURSIVE_MUTEX_INITIALIZER_NP;
 const pthread_cond_t condition_var::cond  = PTHREAD_COND_INITIALIZER;
 
-mutex::mutex( )
+seq24mutex::seq24mutex( )
 {
     m_mutex_lock = recmutex;
 }
 
 void
-mutex::lock( )
+seq24mutex::lock( )
 {
     pthread_mutex_lock( &m_mutex_lock );
 }
 
 
 void
-mutex::unlock( )
+seq24mutex::unlock( )
 {
     pthread_mutex_unlock( &m_mutex_lock );
 }
diff --git a/src/mutex.h b/src/mutex.h
index 399f8a3..4f1b867 100644
--- a/src/mutex.h
+++ b/src/mutex.h
@@ -24,7 +24,7 @@
 
 #include <pthread.h>
 
-class mutex {
+class seq24mutex {
 
 private:
 
@@ -37,14 +37,14 @@ protected:
 
 public:
 
-    mutex();
+    seq24mutex();
 
     void lock();
     void unlock();
 
 };
 
-class condition_var : public mutex {
+class condition_var : public seq24mutex {
 
 private:
 
diff --git a/src/sequence.h b/src/sequence.h
index 2943946..9da8700 100644
--- a/src/sequence.h
+++ b/src/sequence.h
@@ -153,7 +153,7 @@ class sequence
     long m_rec_vol;
 
     /* locking */
-    mutex m_mutex;
+    seq24mutex m_mutex;
 
     /* used to idenfity which events are ours in the out queue */
     //unsigned char m_tag;
s='left'>Commit message (<a href='/guix/log/gnu/services/science.scm?id=f59aa79ca342ef311a20dafc782adea6eed29b1a&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2021-11-30 01:08:55 +0100'>2021-11-30</span></td><td><a href='/guix/commit/gnu/services/science.scm?id=892f1b7273d57b25940700877a02618fe826cc08'>services: Accept &lt;inferior-package&gt;s in lieu of &lt;package&gt;s.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/services/authentication.scm (fprintd-configuration)
(nslcd-configuration): Substitute file-like objects for package ones.
* gnu/services/cgit.scm (cgit-configuration, opaque-cgit-configuration):
Likewise.
* gnu/services/cups.scm (package-list?, cups-configuration): Likewise.
* gnu/services/dns.scm (verify-knot-configuration)
(ddclient-configuration): Likewise.
* gnu/services/docker.scm (docker-configuration): Likewise.
* gnu/services/file-sharing.scm (transmission-daemon-configuration): Likewise.
* gnu/services/getmail.scm (getmail-configuration): Likewise.
* gnu/services/mail.scm (dovecot-configuration)
(opaque-dovecot-configuration): Likewise.
* gnu/services/messaging.scm (prosody-configuration)
(opaque-prosody-configuration): Likewise.
* gnu/services/monitoring.scm (zabbix-server-configuration)
(zabbix-agent-configuration): Likewise.
* gnu/services/networking.scm (opendht-configuration): Likewise.
* gnu/services/pm.scm (tlp-configuration): Likewise.
* gnu/services/telephony.scm (jami-configuration): Likewise.
* gnu/services/virtualization.scm (libvirt-configuration)
(qemu-guest-agent-configuration): Likewise.
* gnu/services/vpn.scm (openvpn-client-configuration): Likewise.
</span></span></td><td>Tobias Geerinckx-Rice</td></tr>
<tr><td><span title='2020-12-09 12:55:02 +0200'>2020-12-09</span></td><td><a href='/guix/commit/gnu/services/science.scm?id=533935ccf71bef93f2f146fba1b2bb6402559965'>services: science.scm: Add missing copyright headers.</a><span class='msg-avail'>...<span class='msg-tooltip'>This module was always supposed to have the GPL3 header in place.
Follow-up to 8f19e63f760fe02f9969225da2f3f3c36801218f.

* gnu/services/science.scm: Add Copyright headers.
</span></span></td><td>Efraim Flashner</td></tr>