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;
6f'>doc: Fix typo in HACKING.</a><span class='msg-avail'>...<span class='msg-tooltip'>* HACKING (Contributing): s/informations/information/.
</span></span></td><td>Maxim Cournoyer</td></tr>
<tr><td><span title='2020-01-09 23:33:04 +0100'>2020-01-09</span></td><td><a href='/guix/commit/HACKING?id=2d315cd428484537e763d7f7c676dc5fff7995f6'>doc: Move "Commit Access" section from 'HACKING' to the manual.</a><span class='msg-avail'>...<span class='msg-tooltip'>* HACKING (Commit Access): Remove.
(Contributing): Update URL of the manual.
* doc/contributing.texi (Commit Access): New section.
(Submitting Patches): Add cross reference.
</span></span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2020-01-09 23:33:04 +0100'>2020-01-09</span></td><td><a href='/guix/commit/HACKING?id=a7bde77d247ed0765f5378779d67b4668c5d7648'>doc: Add "Tracking Bugs and Patches" section.</a><span class='msg-avail'>...<span class='msg-tooltip'>* doc/contributing.texi (Tracking Bugs and Patches): New section.
(Submitting Patches): Refer to it.
* doc/guix.texi: Update copyright line.
* HACKING (Using emacs-debbugs): Remove.
</span></span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2019-07-13 14:25:19 -0400'>2019-07-13</span></td><td><a href='/guix/commit/HACKING?id=06e1ecbf17fee7fe513ad2808d8175fb3565ae3e'>doc: Update keyserver URL.</a><span class='msg-avail'>...<span class='msg-tooltip'>* HACKING (Commit Access): Change keyserver URL to 'keys.openpgp.org'.
</span></span></td><td>Leo Famulari</td></tr>
<tr><td><span title='2019-02-11 23:23:27 +0100'>2019-02-11</span></td><td><a href='/guix/commit/HACKING?id=6701edbfad62ba9572ffd35497df3db27b208ba5'>HACKING: Update key server.</a><span class='msg-avail'>...<span class='msg-tooltip'>* HACKING (Commit Access): Recommend pool.sks-keyservers.net.
</span></span></td><td>Ludovic Courtès</td></tr>