Remove incorrect use of EXTRA_DIST for man pages

Setting the 'dist_' prefix is the correct way to instruct Automake
to include these files in the distribution.  The EXTRA_DIST variable
is reserved for files which are not covered by the automatic rules.

  http://www.gnu.org/software/automake/manual/automake.html#Basics

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

man/man1/Makefile.am

@@ -1,5 +1,4 @@
-man_MANS = splat.1
-EXTRA_DIST = $(man_MANS)
+dist_man_MANS = splat.1
 
 install-data-local:
 	$(INSTALL) -d -m 0755 "$(DESTDIR)$(mandir)/man1"

man/man5/Makefile.am

@@ -1,5 +1,4 @@
-man_MANS = spl-module-parameters.5
-EXTRA_DIST = $(man_MANS)
+dist_man_MANS = spl-module-parameters.5
 
 install-data-local:
 	$(INSTALL) -d -m 0755 "$(DESTDIR)$(mandir)/man5"