8206445: JImageListTest.java failed in Windows

Added System.gc() call to address unmapped jimage files

Reviewed-by: alanb

test/jdk/ProblemList.txt

@@ -828,7 +828,6 @@ java/awt/im/memoryleak/InputContextMemoryLeakTest.java 8023814 linux-all,solaris
 # core_tools
 
 tools/pack200/CommandLineTests.java                             8059906 generic-all
-tools/jimage/JImageListTest.java                                8206445 windows-all
 
 ############################################################################
 

test/jdk/tools/jimage/JImageListTest.java

@@ -224,6 +224,8 @@ public class JImageListTest extends JImageCliTest {
 
     public static void main(String[] args) throws Throwable {
         new JImageListTest().runTests();
+        // Just to ensure that jimage files will be unmapped
+        System.gc();
     }
 }