In musl libc there is no struct mallinfo and no function mallinf()

--- src/OSD/OSD_MemInfo.cxx.orig
+++ src/OSD/OSD_MemInfo.cxx
@@ -147,8 +147,12 @@
   }
   aFile.close();
 
+  #if defined(__GLIBC__)
   struct mallinfo aMI = mallinfo();
   myCounters[MemHeapUsage] = aMI.uordblks;
+  #else /* XXX not yet coded */
+  myCounters[MemHeapUsage] = 0;
+  #endif
 
 #elif (defined(__APPLE__))
   struct task_basic_info aTaskInfo;