Remove sendfile stub

We now have the `sendfile` syscall implemented in the core repository.
Therefore remove it from here.

Signed-off-by: Sergiu Moga <[email protected]>
Approved-by: Michalis Pappas <[email protected]>
Reviewed-by: Andrei Tatar <[email protected]>
GitHub-Closes: #65

Author: mogasergiu

Makefile.uk

@@ -94,7 +94,6 @@ LIBLWIP_SRCS-$(CONFIG_LWIP_THREADS) += $(LIBLWIP_BASE)/mailbox.c|unikraft
 LIBLWIP_SRCS-$(CONFIG_LWIP_THREADS) += $(LIBLWIP_BASE)/threads.c|unikraft
 LIBLWIP_SRCS-y += $(LIBLWIP_BASE)/init.c|unikraft
 LIBLWIP_SRCS-y += $(LIBLWIP_BASE)/time.c|unikraft
-LIBLWIP_SRCS-y += $(LIBLWIP_BASE)/sendfile.c|unikraft
 LIBLWIP_SRCS-$(CONFIG_LWIP_SOCKET) += $(LIBLWIP_BASE)/sockets.c|unikraft
 LIBLWIP_SOCKETS_FLAGS-$(call gcc_version_ge,8,0) += -Wno-cast-function-type
 LIBLWIP_SRCS-y += $(LIBLWIP_EXTRACTED)/core/init.c