gcc-20010409 compilation fails on Tru64 Unix

[Per Wigren <wigren at home dot se>]

bison  -o op$$.c objc-parse.y ; \
mv -f op$$.c objc-parse.c
cc -c  -DIN_GCC    -g   -DHAVE_CONFIG_H -DGENERATOR_FILE    -I. -I. -I. -I./. 
-I./config -I./../include ./gengenrtl.c
cc: Warning: ./system.h, line 293: In this declaration, parameter 1 has a 
different type than specified in an earlier declaration of this function. 
(mismatparam)
extern PTR sbrk PARAMS ((int));
-----------^
cc: Error: ./system.h, line 293: In this declaration, the type of "sbrk" is 
not compatible with the type of a previous declaration of "sbrk" at line 
number 657 in file /usr/include/unistd.h. (notcompat)
extern PTR sbrk PARAMS ((int));
-----------^
cc: Warning: ./system.h, line 341: In this declaration, parameter 2 has a 
different type than specified in an earlier declaration of this function. 
(mismatparam)
extern int setrlimit PARAMS ((int, const struct rlimit *));
-----------^
cc: Error: ./system.h, line 341: In this declaration, the type of "setrlimit" 
is not compatible with the type of a previous declaration of "setrlimit" at 
line number 209 in file /usr/include/sys/resource.h. (notcompat)
extern int setrlimit PARAMS ((int, const struct rlimit *));
-----------^
cc: Warning: ./../include/libiberty.h, line 52: In this declaration, 
parameter 1 has a different type than specified in an earlier declaration of 
this function. (mismatparam)
extern char *basename PARAMS ((const char *));
-------------^
cc: Error: ./../include/libiberty.h, line 52: In this declaration, the type 
of "basename" is not compatible with the type of a previous declaration of 
"basename" at line number 163 in file /usr/include/string.h. (notcompat)
extern char *basename PARAMS ((const char *));
-------------^
cc: Error: ./system.h, line 561: In this declaration, "char" cannot be 
combined with "_Bool". (typeconflict)
typedef char _Bool;
-------------^
gmake[1]: *** [gengenrtl.o] Error 1
gmake[1]: Leaving directory `/pc/usr/download/Tru64/build/gcc-20010409/gcc'
gmake: *** [all-gcc] Error 2
bash-2.05#