[Xymon] Compile error 4.3.9

make[1]: Entering directory /tmp/xymon-4.3.9/xymonnet' gcc -g -O2 -Wall -Wno-unused -Wno-pointer-sign -D_REENTRANT -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64 -DLINUX -I. -I/tmp/xymon-4.3.9/include -c -o httptest.o httptest.c httptest.c: In function âadd_http_testâ: httptest.c:552:84: error: âerrnoâ undeclared (first use in this function) httptest.c:552:84: note: each undeclared identifier is reported only once for each function it appears in make[1]: *** [httptest.o] Error 1 make[1]: Leaving directory /tmp/xymon-4.3.9/xymonnet' make: *** [xymonnet-build] Error 2