admin/build-doc: fix dependency checks

http://tracker.ceph.com/issues/11857 Fixes: #11857

Signed-off-by: John Spray <john.spray@redhat.com>
(cherry picked from commit 539c1ba)

Conflicts:
	admin/build-doc
            Insert lines at appropriate spot

admin/build-doc

@@ -1,7 +1,5 @@
 #!/bin/sh
 
-set -e
-
 cd "$(dirname "$0")"
 cd ..
 TOPDIR=`pwd`
@@ -51,6 +49,10 @@ if [ ! -e build-doc/doxygen/xml ]; then
     doxygen
 fi
 
+# Don't enable -e until after running all the potentially-erroring checks
+# for availability of commands
+set -e
+
 cat src/osd/PG.h src/osd/PG.cc | doc/scripts/gen_state_diagram.py > doc/dev/peering_graph.generated.dot
 
 cd build-doc