Remove custom install-data-local for headers

Rather than use a custom install target it is cleaner to define
a 'kerneldir' and set 'kernel_HEADERS' appropriately.  This
allows us to leverage the standing configure install support.

Additionally, I took this opertunity add the missing make files
to the include subdirectories.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>

include/rpc/Makefile.am

@@ -0,0 +1,14 @@
+COMMON_H =
+
+KERNEL_H = \
+	$(top_srcdir)/include/rpc/types.h \
+	$(top_srcdir)/include/rpc/xdr.h
+
+USER_H =
+
+EXTRA_DIST = $(COMMON_H) $(KERNEL_H) $(USER_H)
+
+if CONFIG_KERNEL
+kerneldir = /usr/src/spl-$(SPL_META_VERSION)-$(SPL_META_RELEASE)/$(LINUX_VERSION)/rpc
+kernel_HEADERS = $(KERNEL_H)
+endif