Fix another square root performance bug

Bug: 71686706

This one actually fixes the above issue in AOSP.

Without this, sqrt() tended to force evaluation of the argument
to twice the the requested precision, which clearly didn't scale.
For some reason, that didn't seem to be reproducible for all
calculator versions.

Test: Calculator tests + CR tests
Change-Id: I2cc0053f5e27d5d0364c707fe580aa246bbf99d0
diff --git a/src/com/hp/creals/CR.java b/src/com/hp/creals/CR.java
index 9e10b51..e7cd26a 100644
--- a/src/com/hp/creals/CR.java
+++ b/src/com/hp/creals/CR.java
@@ -1502,7 +1502,7 @@
     final int fp_op_prec = 60;
     protected BigInteger approximate(int p) {
         int max_op_prec_needed = 2*p - 1;
-        int msd = op.msd(max_op_prec_needed);
+        int msd = op.iter_msd(max_op_prec_needed);
         if (msd <= max_op_prec_needed) return big0;
         int result_msd = msd/2;                 // +- 1
         int result_digits = result_msd - p;     // +- 2