[psaux] Use `FT_SqrtFixed`.

* src/psaux/cffdecode.c <cff_op_sqrt>: Call `FT_SqrtFixed`.
* src/psaux/psintrp.c <cf2_escSQRT>: Ditto.

src/psaux/cffdecode.c

@@ -1753,22 +1753,9 @@
 
           /* without upper limit the loop below might not finish */
           if ( args[0] > 0x7FFFFFFFL )
-            args[0] = 0xB504F3L;    /* sqrt( 32768.0 ) */
+            args[0] = 0xB504F4L;    /* sqrt( 32768.0044 ) */
           else if ( args[0] > 0 )
-          {
-            FT_Fixed  root = 1 << ( ( 17 + FT_MSB( args[0] ) ) >> 1 );
-            FT_Fixed  new_root;
-
-
-            for (;;)
-            {
-              new_root = ( root + FT_DivFix( args[0], root ) + 1 ) >> 1;
-              if ( new_root == root )
-                break;
-              root = new_root;
-            }
-            args[0] = new_root;
-          }
+            args[0] = (FT_Fixed)FT_SqrtFixed( args[0] );
           else
             args[0] = 0;
           args++;

src/psaux/psintrp.c

@@ -2276,22 +2276,7 @@
 
                     arg = cf2_stack_popFixed( opStack );
                     if ( arg > 0 )
-                    {
-                      /* initial guess based on the most significant bit */
-                      FT_Fixed  root = 1 << ( ( 17 + FT_MSB( arg ) ) >> 1 );
-                      FT_Fixed  new_root;
-
-
-                      /* Babylonian method */
-                      for (;;)
-                      {
-                        new_root = ( root + FT_DivFix( arg, root ) + 1 ) >> 1;
-                        if ( new_root == root )
-                          break;
-                        root = new_root;
-                      }
-                      arg = new_root;
-                    }
+                      arg = (CF2_F16Dot16)FT_SqrtFixed( arg );
                     else
                       arg = 0;