5261 libm should stop using synonyms.h

*** 54,64 ****
   * The decimal values may be used, provided that the compiler will convert
   * from decimal to binary accurately enough to produce the hexadecimal values
   * shown.
   */
  
! #pragma weak atan2l = __atan2l
  
  #include "libm.h"
  #include "longdouble.h"
  
  static const long double
--- 54,64 ----
   * The decimal values may be used, provided that the compiler will convert
   * from decimal to binary accurately enough to produce the hexadecimal values
   * shown.
   */
  
! #pragma weak __atan2l = atan2l
  
  #include "libm.h"
  #include "longdouble.h"
  
  static const long double