Break out of potentially infinite rescaling loop after 20 iterations

Author: martin-frbg

SRC/clartg.f

@@ -161,7 +161,7 @@ SUBROUTINE CLARTG( F, G, CS, SN, R )
          FS = FS*SAFMN2
          GS = GS*SAFMN2
          SCALE = SCALE*SAFMN2
-         IF( SCALE.GE.SAFMX2 )
+         IF( SCALE.GE.SAFMX2 .AND. COUNT .LT. 20)
      $      GO TO 10
       ELSE IF( SCALE.LE.SAFMN2 ) THEN
          IF( G.EQ.CZERO.OR.SISNAN( ABS( G ) ) ) THEN