#6 mem.cc won't compile

[Anonymous]

make -C src all
make -C core all
c++ -g -Wall -Os -DPREFIX=\"/usr\" -DSBINDIR=\"/usr/sbin\" -
DMANDIR=\"/usr/share/man\" -DDATADIR=\"/usr/share\" -c hw.cc -o
hw.o
c++ -g -Wall -Os -DPREFIX=\"/usr\" -DSBINDIR=\"/usr/sbin\" -
DMANDIR=\"/usr/share/man\" -DDATADIR=\"/usr/share\" -c main.cc
-o main.o
c++ -g -Wall -Os -DPREFIX=\"/usr\" -DSBINDIR=\"/usr/sbin\" -
DMANDIR=\"/usr/share/man\" -DDATADIR=\"/usr/share\" -c print.cc
-o print.o
c++ -g -Wall -Os -DPREFIX=\"/usr\" -DSBINDIR=\"/usr/sbin\" -
DMANDIR=\"/usr/share/man\" -DDATADIR=\"/usr/share\" -c mem.cc
-o mem.o
mem.cc: In function `long long unsigned int get_sysconf_size()':
mem.cc:43: error: '_SC_PHYS_PAGES' was not declared in this
scope
make[2]: *** [mem.o] Error 1
make[1]: *** [core] Error 2
make: *** [all] Error 2

Any help would be greatly appreciated.

Thanks