5261 libm should stop using synonyms.h

@@ -25,11 +25,11 @@
 /*
  * Copyright 2006 Sun Microsystems, Inc.  All rights reserved.
  * Use is subject to license terms.
  */
 
-#pragma weak catanh = __catanh
+#pragma weak __catanh = catanh
 
 /* INDENT OFF */
 /*
  * z := x + iy
  * catanh(z)    = -i catan(iz)