Remove unused libm/posix.lib.so from lwip_lx.run

Prevents integration failures like follows if the libraries were not
built already in the build directory.

  Missing boot modules: libm.lib.so posix.lib.so
  Makefile:323: recipe for target 'run/lwip_lx' failed

repos/libports/run/lwip_lx.run

@@ -62,7 +62,7 @@ install_config $config
 
 set boot_modules {
 	core init timer linux_nic_drv
-	ld.lib.so libc.lib.so vfs.lib.so libm.lib.so posix.lib.so vfs_lwip.lib.so test-lwip_httpsrv
+	ld.lib.so libc.lib.so vfs.lib.so vfs_lwip.lib.so test-lwip_httpsrv
 }
 
 build_boot_image $boot_modules