Fix maintainer-install

It wasn't running `composer-dump-autoload-dev` (the prerequisite in
the root Makefile doesn't work -- we need to recurse into ./webapp).

Makefile

@@ -5,7 +5,8 @@
 export TOPDIR = $(shell pwd)
 
 REC_TARGETS=build domserver install-domserver judgehost install-judgehost \
-            docs install-docs inplace-install inplace-uninstall maintainer-conf \
+            docs install-docs \
+            maintainer-conf maintainer-install inplace-install inplace-uninstall \
             composer-dependencies composer-dependencies-dev
 
 # Global Makefile definitions
@@ -198,7 +199,7 @@ inplace-conf-common: dist
 # Install the system in place: don't really copy stuff, but create
 # symlinks where necessary to let it work from the source tree.
 # This stuff is a hack!
-maintainer-install: inplace-install composer-dump-autoload-dev
+maintainer-install: inplace-install
 inplace-install: build domserver-create-dirs judgehost-create-dirs
 inplace-install-l:
 # Replace libjudgedir with symlink to prevent lots of symlinks:
@@ -316,5 +317,4 @@ clean-autoconf:
         $(addprefix inplace-,conf conf-common install uninstall) \
         $(addprefix maintainer-,conf install) clean-autoconf config distdocs \
         composer-dependencies composer-dependencies-dev \
-        composer-dump-autoload-dev \
         coverity-conf coverity-build