Fix probable prime confidence calculations.

This fix from upstream fixes a problem where the number of iterations
used to confirm that a number is prime was based off the length of the
key rather than the length of the factors p and q.  Fewer iterations
are called for for a longer number, so this resulted in a
lower-than-expected confidence in the primality of the key factors.

This only affects apps that use RSAKeyPairGenerator directly (which is
not a public API), rather than those that use
java.security.KeyPairGenerator.

Upstream commits:

https://github.com/bcgit/bc-java/commit/73780ac522b7795fc165630aba8d5f5729acc839
https://github.com/bcgit/bc-java/commit/22467b6e8fe19717ecdf201c0cf91bacf04a55ad

Bug: 79148652
Test: make
Change-Id: I759a226afc9dbd948611eed99ad89ab7f59b09f8
(cherry picked from commit 91719e3c1be2eb206a50a49a5d172884d65eba1c)

bcprov/src/main/java/org/bouncycastle/crypto/generators/RSAKeyPairGenerator.java

diff --git a/bcprov/src/main/java/org/bouncycastle/crypto/generators/RSAKeyPairGenerator.java b/bcprov/src/main/java/org/bouncycastle/crypto/generators/RSAKeyPairGenerator.java
index f23f654..beb1aee 100644
--- a/bcprov/src/main/java/org/bouncycastle/crypto/generators/RSAKeyPairGenerator.java
+++ b/bcprov/src/main/java/org/bouncycastle/crypto/generators/RSAKeyPairGenerator.java
@@ -20,12 +20,10 @@
     private static final BigInteger ONE = BigInteger.valueOf(1);
 
     private RSAKeyGenerationParameters param;
-    private int iterations;
 
     public void init(KeyGenerationParameters param)
     {
         this.param = (RSAKeyGenerationParameters)param;
-        this.iterations = getNumberOfIterations(this.param.getStrength(), this.param.getCertainty());
     }
 
     public AsymmetricCipherKeyPair generateKeyPair()
@@ -191,6 +189,8 @@
 
     protected boolean isProbablePrime(BigInteger x)
     {
+        int iterations = getNumberOfIterations(x.bitLength(), param.getCertainty());
+
         /*
          * Primes class for FIPS 186-4 C.3 primality checking
          */