package/libtirpc: fix musl build

The fix includes:
  1) Defining rpcent for non-Glibc's
  2) Using a local queue implementation

1) Defining rpcent for non-Glibc's
musl does not define rpcent. Since musl does not provide a __MUSL__ macro we
add a check for non-Glibc's to the existing uClibc patch.

2) Using a local queue implementation
musl does not provide sys/queue.h. We borrow a compatible queue implementation
from the NetBSD project.

Fixes:
http://autobuild.buildroot.net/results/f93/f93f0be26b5a25b953ea7f909037c1f45a83f686/
http://autobuild.buildroot.net/results/c53/c537a76d17012821ed5a6f4170f759efd4d269b0/
http://autobuild.buildroot.net/results/e3c/e3c5be7dca753f7494e8680894f516a8cdc89843/
http://autobuild.buildroot.net/results/2bb/2bb2e314f23b5ba48bb6e0c4fc7e52032fa5d76b/



and many more.

Signed-off-by: Jörg Krause <joerg.krause@embedded.rocks>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>