lxc: bump to 2.1.0

Bump LXC package from 1.1.5 to 2.1.0. Version 2.x includes many
improvements and optimizations.

https://linuxcontainers.org/lxc/news/

Some tools like lxc-top are rewritten in C and are no longer broken and
dependent on lua.

Signed-off-by: Marko Ratkaj <marko.ratkaj@sartura.hr>

utils/lxc/patches/015-getline.patch

@@ -1,6 +1,6 @@
 --- a/src/lxc/utils.h
 +++ b/src/lxc/utils.h
-@@ -41,11 +41,7 @@ extern int mkdir_p(const char *dir, mode
+@@ -59,11 +59,7 @@ extern int mkdir_p(const char *dir, mode_t mode);
  extern char *get_rundir(void);
  
  /* Define getline() if missing from the C library */