6673277: Thread unsafe lazy initialization code in sun.security.provider.certpath.*Checker classes

Summary: make supportedExts variable non-static
Reviewed-by: vinnie

src/share/classes/sun/security/provider/certpath/ConstraintsChecker.java

@@ -59,7 +59,7 @@ class ConstraintsChecker extends PKIXCertPathChecker {
     private int i;
     private NameConstraintsExtension prevNC;
 
-    private static Set<String> supportedExts;
+    private Set<String> supportedExts;
 
     /**
      * Creates a ConstraintsChecker.

src/share/classes/sun/security/provider/certpath/KeyChecker.java

@@ -50,7 +50,7 @@ class KeyChecker extends PKIXCertPathChecker {
     private CertSelector targetConstraints;
     private int remainingCerts;
 
-    private static Set<String> supportedExts;
+    private Set<String> supportedExts;
 
     /**
      * Default Constructor

src/share/classes/sun/security/provider/certpath/PolicyChecker.java

@@ -68,7 +68,7 @@ class PolicyChecker extends PKIXCertPathChecker {
     private int inhibitAnyPolicy;
     private int certIndex;
 
-    private static Set<String> supportedExts;
+    private Set<String> supportedExts;
 
     private static final Debug debug = Debug.getInstance("certpath");
     static final String ANY_POLICY = "2.5.29.32.0";