5261 libm should stop using synonyms.h

*** 28,38 ****
  
          .file "exp2.s"
  
  #include "libm.h"
  LIBM_ANSI_PRAGMA_WEAK(exp2,function)
- #include "libm_synonyms.h"
  
          ENTRY(exp2)
          movl    8(%esp),%ecx            / ecx <-- hi_32(x)
          andl    $0x7fffffff,%ecx        / ecx <-- hi_32(|x|)
          cmpl    $0x3ff00000,%ecx        / Is |x| < 1?
--- 28,37 ----