Fix ecp_gen_keypair()

Too few tries caused failures for some curves (esp. secp224k1)
diff --git a/ChangeLog b/ChangeLog
index 2f6a3c5..7f7726b 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,10 @@
 PolarSSL ChangeLog (Sorted per branch, date)
 
+= PolarSSL 1.3 branch
+Bugfix
+   * ecp_gen_keypair() does more tries to prevent failure because of
+     statistics
+
 = PolarSSL 1.3.4 released on 2014-01-27
 Features
    * Support for the Koblitz curves: secp192k1, secp224k1, secp256k1