Enable Valgrind support in the API suite

It was accidentally left out when the test system was refactored.

test/scripts/valgrind.sh

@@ -8,7 +8,10 @@
 VALGRIND_CMDLINE="valgrind --leak-check=full --show-reachable=yes --track-origins=yes -q"
 
 if [ $VALGRIND -eq 1 ]; then
+    test_runner="$VALGRIND_CMDLINE"
     json_process="$VALGRIND_CMDLINE $json_process"
+else
+    test_runner=""
 fi
 
 valgrind_check() {

test/suites/api/run

@@ -15,7 +15,10 @@ run_test() {
     if [ -x $test_path ]; then
         test_log=$test_log $test_path >$test_log/stdout 2>$test_log/stderr
     else
-        $suite_builddir/${test_name%.c} >$test_log/stdout 2>$test_log/stderr
+        $test_runner $suite_builddir/${test_name%.c} \
+            >$test_log/stdout \
+            2>$test_log/stderr
+        valgrind_check $test_log/stderr || return 1
     fi
 }