5261 libm should stop using synonyms.h

*** 28,38 ****
  
          .file   "copysign.s"
  
  #include "libm.h"
  LIBM_ANSI_PRAGMA_WEAK(copysign,function)
- #include "libm_synonyms.h"
  
          ENTRY(copysign)
          movl    8(%esp),%eax            / eax <-- hi_32(x)
          movl    16(%esp),%ecx           / ecx <-- hi_32(y)
          andl    $0x7fffffff,%eax        / eax <-- hi_32(abs(x))
--- 28,37 ----