Pull in composer dependencies before running make tests

This is because Makefiles implicitly depend on a distributed
tarball (or initialized maintainer/inplace install).
Running `make dist` would be a bit too much, so take this
shortcut.

.github/jobs/configure-checks/setup_configure_image.sh

@@ -7,16 +7,23 @@ distro_id=$(grep "^ID=" /etc/os-release)
 # Install everything for configure and testing
 case $distro_id in
     "ID=fedora")
-        dnf install pkg-config make bats autoconf automake util-linux -y ;;
+        dnf install -y pkg-config make bats autoconf automake util-linux \
+            php-mysqlnd php-xml php-zip
+        ;;
     *)
         apt-get update; apt-get full-upgrade -y
-        apt-get install pkg-config make bats autoconf -y ;;
+        apt-get install -y pkg-config make bats autoconf composer \
+            php-fpm php-gd php-cli php-intl php-mbstring php-mysql \
+            php-curl php-json php-xml php-zip
+        ;;
 esac
 
-# Build the configure file
+# Start from a configured, distribution-ready source tree. Ideally,
+# we'd like to call `make dist` but that depends on LaTeX for building
+# the documentation, so take a shortcut.
 make configure
 
-# Install extra assert statements for bots
+# Install extra assert statements for bats
 cp submit/assert.bash .github/jobs/configure-checks/
 
 # Run the configure tests for this usecase