Allow spl_config.h to be included by dependant packages (updated)

We need dependent packages to be able to include spl_config.h to
build properly.  This was partially solved in commit 0cbaeb1 by using
AH_BOTTOM to #undef common #defines (PACKAGE, VERSION, etc) which
autoconf always adds and cannot be easily removed.  This solution
works as long as the spl_config.h is included before your projects
config.h.  That turns out to be easier said than done.  In particular,
this is a problem when your package includes its config.h using the
-include gcc option which ensures the first thing included is your
config.h.

To handle all cases cleanly I have removed the AH_BOTTOM hack and
replaced it with an AC_CONFIG_HEADERS command.  This command runs
immediately after spl_config.h is written and with a little awk-foo
it strips the offending #defines from the file.  This eliminates
the problem entirely and makes header safe for inclusion.

Also in this change I have removed the few places in the code where
spl_config.h is included.  It is now added to the gcc compile line
to ensure the config results are always available.

Finally, I have also disabled the verbose kernel builds.  If you
want them back you can always build with 'make V=1'.  Since things
are working now they don't need to be on by default.

config/Rules.am

@@ -1,4 +1,4 @@
-DEFAULT_INCLUDES = -I${top_srcdir}
+DEFAULT_INCLUDES = -include ${top_srcdir}/spl_config.h
 
 AM_CFLAGS  = -Wall -Wstrict-prototypes -Werror -Wshadow
 AM_CFLAGS += -D__USE_LARGEFILE64

config/config.awk

@@ -0,0 +1,15 @@
+# Remove default preprocessor define's from config.h
+#   PACKAGE
+#   PACKAGE_BUGREPORT
+#   PACKAGE_NAME
+#   PACKAGE_STRING
+#   PACKAGE_TARNAME
+#   PACKAGE_VERSION
+#   STDC_HEADERS
+#   VERSION
+
+BEGIN { RS = "" ; FS = "\n" }     \
+	!/.#define PACKAGE./ &&   \
+	!/.#define VERSION./ &&   \
+	!/.#define STDC_HEADERS./ \
+	{ print $0"\n" }

config/spl-build.m4

@@ -4,15 +4,12 @@ dnl #
 AC_DEFUN([SPL_AC_CONFIG_KERNEL], [
 	SPL_AC_KERNEL
 
-	dnl # Kernel build make options
-	dnl # KERNELMAKE_PARAMS="V=1"   # Enable verbose module build
-	KERNELMAKE_PARAMS="V=1"
-
 	dnl # -Wall -fno-strict-aliasing -Wstrict-prototypes and other
 	dnl # compiler options are added by the kernel build system.
 	abs_srcdir=`readlink -f ${srcdir}`
 	KERNELCPPFLAGS="$KERNELCPPFLAGS -Wstrict-prototypes -Werror"
-	KERNELCPPFLAGS="$KERNELCPPFLAGS -I${abs_srcdir} -I${abs_srcdir}/include"
+	KERNELCPPFLAGS="$KERNELCPPFLAGS -I${abs_srcdir}/include"
+	KERNELCPPFLAGS="$KERNELCPPFLAGS -include ${abs_srcdir}/spl_config.h"
 
 	if test "${LINUX_OBJ}" != "${LINUX}"; then
 		KERNELMAKE_PARAMS="$KERNELMAKE_PARAMS O=$LINUX_OBJ"