Ensure static fields set during signed jar process

When loading a signed jar file that is on the classpath, such as the
bouncy castle signed JCE jar file, it has been observed that the value
of `restrictedJarVerificationProviders` and `jarVerificationProviders`
are set to `null`. This causes a NullPointerException during the loading
process.

This update moves the static declarations of both
`restrictedJarVerificationProviders` and `jarVerificationProviders` to
be prior to the method call `RestrictedSecurity.checkHashValues()` since
this method call needs both of these fields to be initialized to work
correctly.

Signed-off-by: Jason Katonica <katonica@us.ibm.com>

src/java.base/share/classes/sun/security/jca/Providers.java

@@ -56,14 +56,6 @@ public class Providers {
     // Note volatile immutable object, so no synchronization needed.
     private static volatile ProviderList providerList;
 
-    static {
-        // set providerList to empty list first in case initialization somehow
-        // triggers a getInstance() call (although that should not happen)
-        providerList = ProviderList.EMPTY;
-        providerList = ProviderList.fromSecurityProperties();
-        RestrictedSecurity.checkHashValues();
-    }
-
     private Providers() {
         // empty
     }
@@ -114,6 +106,14 @@ private Providers() {
         "com.sun.crypto.provider.SunJCE",
     };
 
+    static {
+        // set providerList to empty list first in case initialization somehow
+        // triggers a getInstance() call (although that should not happen)
+        providerList = ProviderList.EMPTY;
+        providerList = ProviderList.fromSecurityProperties();
+        RestrictedSecurity.checkHashValues();
+    }
+
     // Return Sun provider.
     // This method should only be called by
     // sun.security.util.ManifestEntryVerifier and java.security.SecureRandom.