Use new libosmocore logging lock API

Since libosmocore Id7711893b34263baacac6caf4d489467053131bb, a new API
log_enable_multithread() is available which takes care of protecting
logging infrastructure from us (and actually does it correctly since we
cannot protect internal libosmocore structures from osmo-trx).

Let's drop all mutex related code from osmo-trx logging infra and simply
rely on libosmocore's.

Related: OS#4088
Change-Id: I519d0f30bce871005ca26b90177ea4aa4839360a
diff --git a/CommonLibs/Logger.cpp b/CommonLibs/Logger.cpp
index 5db7f87..89e13e5 100644
--- a/CommonLibs/Logger.cpp
+++ b/CommonLibs/Logger.cpp
@@ -48,9 +48,11 @@
 	int neednl = (mlen==0 || mStream.str()[mlen-1] != '\n');
 	const char *fmt = neednl ? "%s\n" : "%s";
 
-	log_mutex_lock_canceldisable(&old_state);
+	/* print related function called inside a C++ destructor, use pthread_setcancelstate() APIs.
+	   See osmo-trx commit 86be40b4eb762d5c12e8e3f7388ca9f254e77b36 for more information */
+	pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &old_state);
 	LOGPSRC(mCategory, mPriority, filename, line, fmt, mStream.str().c_str());
-	log_mutex_unlock_canceldisable(old_state);
+	pthread_setcancelstate(old_state, NULL);
 }
 
 ostringstream& Log::get()