new var DIST_CONTRIB adds useful things for packagers from contrib/ to EXTRA_DIST

Makefile.am

@@ -32,6 +32,11 @@ OSX_PLIST=$(top_builddir)/share/qt/Info.plist #not installed
 OSX_QT_TRANSLATIONS = da,de,es,hu,ru,uk,zh_CN,zh_TW
 
 DIST_DOCS = $(wildcard doc/*.md) $(wildcard doc/release-notes/*.md)
+DIST_CONTRIB = $(top_srcdir)/contrib/bitcoin-cli.bash-completion \
+	       $(top_srcdir)/contrib/bitcoin-tx.bash-completion \
+	       $(top_srcdir)/contrib/bitcoind.bash-completion \
+	       $(top_srcdir)/contrib/init \
+	       $(top_srcdir)/contrib/rpm
 
 BIN_CHECKS=$(top_srcdir)/contrib/devtools/symbol-check.py \
            $(top_srcdir)/contrib/devtools/security-check.py
@@ -204,7 +209,7 @@ endif
 
 dist_noinst_SCRIPTS = autogen.sh
 
-EXTRA_DIST = $(top_srcdir)/share/genbuild.sh qa/pull-tester/rpc-tests.py qa/rpc-tests $(DIST_DOCS) $(WINDOWS_PACKAGING) $(OSX_PACKAGING) $(BIN_CHECKS)
+EXTRA_DIST = $(top_srcdir)/share/genbuild.sh qa/pull-tester/rpc-tests.py qa/rpc-tests $(DIST_CONTRIB) $(DIST_DOCS) $(WINDOWS_PACKAGING) $(OSX_PACKAGING) $(BIN_CHECKS)
 
 CLEANFILES = $(OSX_DMG) $(BITCOIN_WIN_INSTALLER)