autoconf and launchd plist for zpool-autoimport.sh
Use makefile variables rather than hard-coded paths for $sbindir.
Use full path to zfs command in the autoimport script.
Stop redefining zfs_sleep_until.

ZOL introduced zfs_delay.h for the kernel context only. Move our
kernel version of zfs_sleep_until into zfs_delay.h, and do not
include zfs_delay.h in zfs_context_userland.h.

Also, just as ZOL does, we can use nanosleep in our userland context.
add declaration for mach_vm_pressure_monitor
Remove two old debug panics from avl.c
Define the custom-icon constants only once
Fix a Wparentheses warning
Remove defunct zfs_get_snapused_int()

zfs_get_snapused_int() was replaced with lzc_snaprange_space() in
https://github.com/illumos/illumos-gate/commit/4445fffbbb1ea25fd0e9ea68b9380dd7a6709025
Fix three Wimplicit-function-declaration warnings in spa.c

libkern/OSKextLib.h has the declarations for OSKextRetainKextWithLoadTag,
OSKextGetCurrentLoadTag, and OSKextReleaseKextWithLoadTag.
Restore declaration of zfs_zevent_fd_hold

Now that zfs_zevent_fd_hold has been ported, its declaration should
not be commented out in the header.
Eliminate Wimplicit-function-declaration for cv_wait_io() in userland context.
Replace deprecated vsprintf with vsnprintf in log_internal()
Make the check for Core Storage LV more forgiving.
Use getcpuid from spl for kernel context.
Move KERNEL_MODPREFIX to ZFS_AC_CONFIG_ALWAYS.

Always configure KERNEL_MODPREFIX because --with-config=user needs
it in order to know where to find the custom volume icon.
Merge commit '4afe1f31aa0a2813e92af5c1cf0624dc4f1c47ed' into pathfix

Conflicts:
scripts/zpool-autoimport.sh.in
Merge branch 'pathfix' of https://github.com/glessard/zfs into glessard-pathfix

Conflicts:
	scripts/zpool-autoimport.sh.in
Merge branch 'glessard-pathfix'
Add OS X template-derived scripts to .gitignore