gcc-20001204 i586-sco-sysv5uw7.1.0 build failure

[RDBrown at mira dot net]

/devel/src/gcc-20001204.chk/gcc/xgcc -B/devel/src/gcc-20001204.chk/gcc/ \
 -B/usr/local/i586-sco-sysv5uw7.1.0/bin/ \
 -B/usr/local/i586-sco-sysv5uw7.1.0/lib/ \
 -isystem /usr/local/i586-sco-sysv5uw7.1.0/include -DHAVE_CONFIG_H -I. \
 -I../../../../gcc-20001204/libstdc++-v3/libmath -I.. \
 -I../../../../gcc-20001204/libstdc++-v3/include -I../include -g -O2 -c \
 ../../../../gcc-20001204/libstdc++-v3/libmath/signbit.c  -fPIC -DPIC \
 -o .libs/signbit.o
In file included from ../../../../gcc-20001204/libstdc++-v3/libmath/signbit.c:32:
../../../../gcc-20001204/libstdc++-v3/libmath/mathconf.h:205:7: #error "We need INFINITE_P"
make[4]: *** [signbit.lo] Error 1
make[4]: Leaving directory `/devel/src/gcc-20001204.chk/i586-sco-sysv5uw7.1.0/libstdc++-v3/libmath'
make[3]: *** [all-recursive] Error 1
make[3]: Leaving directory `/devel/src/gcc-20001204.chk/i586-sco-sysv5uw7.1.0/libstdc++-v3'
make[2]: *** [all-recursive-am] Error 2
make[2]: Leaving directory `/devel/src/gcc-20001204.chk/i586-sco-sysv5uw7.1.0/libstdc++-v3'
make[1]: *** [all-target-libstdc++-v3] Error 2
make[1]: Leaving directory `/devel/src/gcc-20001204.chk'
make: *** [bootstrap] Error 2

UnixWare 2 & UnixWare 7 have <ieeefp.h>. Shouldn't configure have found
and used `finite' or `fpclass'?

   isnan, isnand, isnanf, finite, fpclass, unordered -- determine type of
   floating-point number 
   
Synopsis

   include <ieeefp.h>

   int isnand (double dsrc);
   int isnanf (float fsrc);
   int finite (double dsrc);

   fpclass_t fpclass (double dsrc);

...

   include <math.h>

   int isnan (double dsrc);

Description

...
   
   fpclass returns the class that dsrc belongs to. The 10 possible
   classes are as follows:
   
...
          
   finite returns true (1) if the argument dsrc is neither infinity nor
   NaN; otherwise it returns false (0).
   
...
   
   None of these routines generates exceptions, even for signaling NaNs.