isnan-nolibm, isnanl-nolibm: fix compilation error

[Bruno Haible]

These modules fail to compile with SunPRO C 5.0 and Compaq C 6.4, because
these compilers refuse to compile statically initialized variables whose
initializers contains a NaN or Infinity. I'm applying this workaround.

2007-03-11  Bruno Haible  <address@hidden>

        * lib/isnan.c (rpl_isnan, rpl_isnanl): Work around bug regarding
        initializers in SunPRO C and Compaq C compilers.

*** lib/isnan.c 25 Feb 2007 02:35:37 -0000      1.2
--- lib/isnan.c 11 Mar 2007 22:35:15 -0000
***************
*** 58,78 ****
  #ifdef KNOWN_EXPBIT0_LOCATION
    /* Be careful to not do any floating-point operation on x, such as x == x,
       because x may be a signaling NaN.  */
    static memory_double nan = { L_(0.0) / L_(0.0) };
    static DOUBLE plus_inf = L_(1.0) / L_(0.0);
    static DOUBLE minus_inf = -L_(1.0) / L_(0.0);
!   memory_double m;
  
!   /* A NaN can be recognized through its exponent.  But exclude +Infinity and
!      -Infinity, which have the same exponent.  */
!   m.value = x;
!   if (((m.word[EXPBIT0_WORD] ^ nan.word[EXPBIT0_WORD])
!        & (EXP_MASK << EXPBIT0_BIT))
!       == 0)
!     return (memcmp (&m.value, &plus_inf, sizeof (DOUBLE)) != 0
!           && memcmp (&m.value, &minus_inf, sizeof (DOUBLE)) != 0);
!   else
!     return 0;
  #else
    /* The configuration did not find sufficient information.  Give up about
       the signaling NaNs, handle only the quiet NaNs.  */
--- 58,89 ----
  #ifdef KNOWN_EXPBIT0_LOCATION
    /* Be careful to not do any floating-point operation on x, such as x == x,
       because x may be a signaling NaN.  */
+ # if defined __SUNPRO_C || defined __DECC
+   /* The Sun C 5.0 compilers and the Compaq (ex-DEC) 6.4 compilers don't
+      recognize the initializers as constant expressions.  */
+   memory_double nan;
+   DOUBLE plus_inf = L_(1.0) / L_(0.0);
+   DOUBLE minus_inf = -L_(1.0) / L_(0.0);
+   nan.value = L_(0.0) / L_(0.0);
+ # else
    static memory_double nan = { L_(0.0) / L_(0.0) };
    static DOUBLE plus_inf = L_(1.0) / L_(0.0);
    static DOUBLE minus_inf = -L_(1.0) / L_(0.0);
! # endif
!   {
!     memory_double m;
  
!     /* A NaN can be recognized through its exponent.  But exclude +Infinity 
and
!        -Infinity, which have the same exponent.  */
!     m.value = x;
!     if (((m.word[EXPBIT0_WORD] ^ nan.word[EXPBIT0_WORD])
!        & (EXP_MASK << EXPBIT0_BIT))
!       == 0)
!       return (memcmp (&m.value, &plus_inf, sizeof (DOUBLE)) != 0
!             && memcmp (&m.value, &minus_inf, sizeof (DOUBLE)) != 0);
!     else
!       return 0;
!   }
  #else
    /* The configuration did not find sufficient information.  Give up about
       the signaling NaNs, handle only the quiet NaNs.  */