5261 libm should stop using synonyms.h

*** 28,38 ****
  
          .file "exp2l.s"
  
  #include "libm.h"
  LIBM_ANSI_PRAGMA_WEAK(exp2l,function)
- #include "libm_synonyms.h"
  
          ENTRY(exp2l)
          movl    16(%rsp),%ecx           / cx <--sign&bexp(x)
          andl    $0x7fff,%ecx            / ecx <-- zero_xtnd(bexp(x))
          cmpl    $0x3fff,%ecx            / Is |x| <= 1?
--- 28,37 ----