There is no moncontrol() in musl libc.

--- source/darkplaces/sys_shared.c	2015-01-13 19:56:16.000000000 +0100
+++ source/darkplaces/sys_shared.c	2015-08-30 09:24:54.839064473 +0200
@@ -69,7 +69,7 @@
 	else
 		moncleanup();
 #endif
-#elif defined(__linux__) || defined(__FreeBSD__)
+#elif (defined(__linux__) && defined(__GLIBC__)) || defined(__FreeBSD__)
 	extern int moncontrol(int);
 	moncontrol(enable);
 #endif
