5261 libm should stop using synonyms.h

*** 90,101 ****
   *      Special case:
   *         erf(inf)  = 1
   *         erfc(inf) = 0
   */
  
! #pragma weak erfl = __erfl
! #pragma weak erfcl = __erfcl
  
  #include "libm.h"
  #include "longdouble.h"
  
  static long double
--- 90,101 ----
   *      Special case:
   *         erf(inf)  = 1
   *         erfc(inf) = 0
   */
  
! #pragma weak __erfl = erfl
! #pragma weak __erfcl = erfcl
  
  #include "libm.h"
  #include "longdouble.h"
  
  static long double