Fix make mode=debug build

When building with -O0 we get:

 bsd/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_ioctl.o: In
 function `zfs_ioc_destroy_snaps_nvl':
 (...)/bsd/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_ioctl.c:3265:
 undefined reference to `zvol_remove_minor'

Looks like the problem is that the missing symbol,
`zvol_remove_minor', referenced from zfs_ioctl.o is not in the zvol.o
because it's not defined, because it is inside '#ifdef NOTYET' block
(which is off). It works in the normal build because when compiled
with -O2 (and even with -O1), the reference to zvol_remove_minor in
zfs_ioctl.c is optimized away.

This patch puts the block using zvol_remove_minor also inside '#ifdef
NOTYET' to be consistent.

Signed-off-by: Tomasz Grabiec <tgrabiec@cloudius-systems.com>
Fix linker error in make mode=debug

This is a workaround for linker error when compiling with -O0

  `.text._Z9safe_loadIcEbPKT_RS0_' referenced in section `.text.fixup'
  of core/mmu.o: defined in discarded section
  `.text._Z9safe_loadIcEbPKT_RS0_[_Z9safe_loadIcEbPKT_RS0_]' of
  core/mmu.o

The safe_load() template is used in both runtime.cc and core/mmu.cc
but the linker keeps it only in one section discarding the other.

Signed-off-by: Tomasz Grabiec <tgrabiec@cloudius-systems.com>