Update build system and packaging

Minimal changes required to integrate the SPL sources in to the
ZFS repository build infrastructure and packaging.

Build system and packaging:
  * Renamed SPL_* autoconf m4 macros to ZFS_*.
  * Removed redundant SPL_* autoconf m4 macros.
  * Updated the RPM spec files to remove SPL package dependency.
  * The zfs package obsoletes the spl package, and the zfs-kmod
    package obsoletes the spl-kmod package.
  * The zfs-kmod-devel* packages were updated to add compatibility
    symlinks under /usr/src/spl-x.y.z until all dependent packages
    can be updated.  They will be removed in a future release.
  * Updated copy-builtin script for in-kernel builds.
  * Updated DKMS package to include the spl.ko.
  * Updated stale AUTHORS file to include all contributors.
  * Updated stale COPYRIGHT and included the SPL as an exception.
  * Renamed README.markdown to README.md
  * Renamed OPENSOLARIS.LICENSE to LICENSE.
  * Renamed DISCLAIMER to NOTICE.

Required code changes:
  * Removed redundant HAVE_SPL macro.
  * Removed _BOOT from nvpairs since it doesn't apply for Linux.
  * Initial header cleanup (removal of empty headers, refactoring).
  * Remove SPL repository clone/build from zimport.sh.
  * Use of DEFINE_RATELIMIT_STATE and DEFINE_SPINLOCK removed due
    to build issues when forcing C99 compilation.
  * Replaced legacy ACCESS_ONCE with READ_ONCE.
  * Include needed headers for `current` and `EXPORT_SYMBOL`.

Reviewed-by: Tony Hutter <hutter2@llnl.gov>
Reviewed-by: Olaf Faaland <faaland1@llnl.gov>
Reviewed-by: Matthew Ahrens <mahrens@delphix.com>
Reviewed-by: Pavel Zakharov <pavel.zakharov@delphix.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
TEST_ZIMPORT_SKIP="yes"
Closes #7556

module/nvpair/fnvpair.c

@@ -508,7 +508,7 @@ fnvpair_value_nvlist(nvpair_t *nvp)
 	return (rv);
 }
 
-#if defined(_KERNEL) && defined(HAVE_SPL)
+#if defined(_KERNEL)
 
 EXPORT_SYMBOL(fnvlist_alloc);
 EXPORT_SYMBOL(fnvlist_free);

module/nvpair/nvpair.c

@@ -24,25 +24,20 @@
  * Copyright (c) 2015, 2017 by Delphix. All rights reserved.
  */
 
-#include <sys/stropts.h>
 #include <sys/debug.h>
 #include <sys/isa_defs.h>
-#include <sys/int_limits.h>
 #include <sys/nvpair.h>
 #include <sys/nvpair_impl.h>
-#include <rpc/types.h>
+#include <sys/types.h>
+#include <sys/strings.h>
 #include <rpc/xdr.h>
 
-#if defined(_KERNEL) && !defined(_BOOT)
-#include <sys/varargs.h>
-#include <sys/ddi.h>
+#if defined(_KERNEL)
 #include <sys/sunddi.h>
 #include <sys/sysmacros.h>
 #else
 #include <stdarg.h>
 #include <stdlib.h>
-#include <string.h>
-#include <strings.h>
 #include <stddef.h>
 #endif
 
@@ -270,7 +265,7 @@ nvlist_nvflag(nvlist_t *nvl)
 static nv_alloc_t *
 nvlist_nv_alloc(int kmflag)
 {
-#if defined(_KERNEL) && !defined(_BOOT)
+#if defined(_KERNEL)
 	switch (kmflag) {
 	case KM_SLEEP:
 		return (nv_alloc_sleep);
@@ -281,7 +276,7 @@ nvlist_nv_alloc(int kmflag)
 	}
 #else
 	return (nv_alloc_nosleep);
-#endif /* _KERNEL && !_BOOT */
+#endif /* _KERNEL */
 }
 
 /*
@@ -1680,7 +1675,7 @@ nvlist_lookup_nvpair_ei_sep(nvlist_t *nvl, const char *name, const char sep,
 			sepp = idxp;
 
 			/* determine the index value */
-#if defined(_KERNEL) && !defined(_BOOT)
+#if defined(_KERNEL)
 			if (ddi_strtol(idxp, &idxep, 0, &idx))
 				goto fail;
 #else
@@ -3320,7 +3315,7 @@ nvs_xdr(nvstream_t *nvs, nvlist_t *nvl, char *buf, size_t *buflen)
 	return (err);
 }
 
-#if defined(_KERNEL) && defined(HAVE_SPL)
+#if defined(_KERNEL)
 static int __init
 nvpair_init(void)
 {

module/nvpair/nvpair_alloc_fixed.c

@@ -24,18 +24,9 @@
  * Use is subject to license terms.
  */
 
-
-
-#include <sys/stropts.h>
 #include <sys/isa_defs.h>
 #include <sys/nvpair.h>
 #include <sys/sysmacros.h>
-#if defined(_KERNEL) && !defined(_BOOT)
-#include <sys/varargs.h>
-#else
-#include <stdarg.h>
-#include <strings.h>
-#endif
 
 /*
  * This allocator is very simple.
@@ -119,6 +110,6 @@ const nv_alloc_ops_t nv_fixed_ops_def = {
 
 const nv_alloc_ops_t *nv_fixed_ops = &nv_fixed_ops_def;
 
-#if defined(_KERNEL) && defined(HAVE_SPL)
+#if defined(_KERNEL)
 EXPORT_SYMBOL(nv_fixed_ops);
 #endif