Simplify get/set NFS4 ACL (openzfs#113)

This removes an extra memory allocation / free from the
NFS4 ACL xattr handler. Initially this was written rather
quickly in the alpha cycle of SCALE and implemented in a
way to ensure that xattr was exactly matching format
used internally in samba's vfs_acl_xattr module. Since
this time a more efficient conversion between the Samba
format and various other ones was added for the purpose
of inclusion in the Kernel NFS server.

This change simplifies conversion between internal NFS ACL and
external xattr representation, but has no impact on userspace
and kernel consumers of this xattr (format does not change).

Signed-off-by: Andrew Walker <[email protected]>

module/Kbuild.in

@@ -438,7 +438,6 @@ ZFS_OBJS_OS := \
 	abd_os.o \
 	arc_os.o \
 	mmp_os.o \
-	nfs41acl_xdr.o \
 	policy.o \
 	qat.o \
 	qat_compress.o \

module/Makefile.in

@@ -53,15 +53,6 @@ FMAKE = env -u MAKEFLAGS make $(FMAKEFLAGS)
 modules-Linux:
 	mkdir -p $(sort $(dir $(spl-objs) $(spl-)))
 	mkdir -p $(sort $(dir $(zfs-objs) $(zfs-)))
-	@# Generate the nfs41acl XDR header.
-	rpcgen -h "@abs_srcdir@/os/linux/zfs/nfs41acl.x" > "@abs_srcdir@/os/linux/zfs/nfs41acl.h"
-	sed -i "/\<rpc\/rpc.h\>/c\\#include \<rpc\/xdr.h\>" "@abs_srcdir@/os/linux/zfs/nfs41acl.h"
-	sed -i "9i #include <sys/sysmacros.h>" "@abs_srcdir@/os/linux/zfs/nfs41acl.h"
-	@# Generate the nfs41acl XDR code.
-	rpcgen -c "@abs_srcdir@/os/linux/zfs/nfs41acl.x" > "@abs_srcdir@/os/linux/zfs/nfs41acl_xdr.c"
-	sed -i "5i #pragma GCC diagnostic push" "@abs_srcdir@/os/linux/zfs/nfs41acl_xdr.c"
-	sed -i "6i #pragma GCC diagnostic ignored \"-Wunused-variable\"" "@abs_srcdir@/os/linux/zfs/nfs41acl_xdr.c"
-	echo "#pragma GCC diagnostic pop" >> "@abs_srcdir@/os/linux/zfs/nfs41acl_xdr.c"
 	@# Build the kernel modules.
 	$(MAKE) -C @LINUX_OBJ@ $(if @KERNEL_CC@,CC=@KERNEL_CC@) \
 		$(if @KERNEL_LD@,LD=@KERNEL_LD@) $(if @KERNEL_LLVM@,LLVM=@KERNEL_LLVM@) \