gcc -DNDEBUG -g -O3 -Wall -Wstrict-prototypes -I. 
-I./Include -DHAVE_CONFIG_H   -c 
./Modules/posixmodule.c -o Modules/posixmodule.o
./Modules/posixmodule.c: In function `posix_nice':
./Modules/posixmodule.c:1270: warning: implicit 
declaration of function `getpriority'
./Modules/posixmodule.c:1270: `PRIO_PROCESS' 
undeclared (first use in this function)
./Modules/posixmodule.c:1270: (Each undeclared 
identifier is reported only once
./Modules/posixmodule.c:1270: for each function it 
appears in.)
make: *** [Modules/posixmodule.o] Error 1

This using gcc version 2.95.3 on what started life as 
a Red Hat 6.0 system.