Determining if the getpassphrase exist failed with the following output:
Change Dir: /usr/lfs/hdd_v1/rc-buildroot-test/scripts/instance-0/output/build/znc-1.7.5/CMakeFiles/CMakeTmp

Run Build Command:"/usr/bin/gmake" "cmTC_835da/fast"
gmake[1]: Entering directory `/usr/lfs/hdd_v1/rc-buildroot-test/scripts/instance-0/output/build/znc-1.7.5/CMakeFiles/CMakeTmp'
/usr/bin/gmake -f CMakeFiles/cmTC_835da.dir/build.make CMakeFiles/cmTC_835da.dir/build
gmake[2]: Entering directory `/usr/lfs/hdd_v1/rc-buildroot-test/scripts/instance-0/output/build/znc-1.7.5/CMakeFiles/CMakeTmp'
Building CXX object CMakeFiles/cmTC_835da.dir/CheckSymbolExists.cxx.o
/usr/lfs/hdd_v1/rc-buildroot-test/scripts/instance-0/output/host/bin/mipsel-linux-g++ --sysroot=/usr/lfs/hdd_v1/rc-buildroot-test/scripts/instance-0/output/host/mipsel-buildroot-linux-uclibc/sysroot    -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64 -Os   -DNDEBUG   -o CMakeFiles/cmTC_835da.dir/CheckSymbolExists.cxx.o -c /usr/lfs/hdd_v1/rc-buildroot-test/scripts/instance-0/output/build/znc-1.7.5/CMakeFiles/CMakeTmp/CheckSymbolExists.cxx
/usr/lfs/hdd_v1/rc-buildroot-test/scripts/instance-0/output/build/znc-1.7.5/CMakeFiles/CMakeTmp/CheckSymbolExists.cxx: In function 'int main(int, char**)':
/usr/lfs/hdd_v1/rc-buildroot-test/scripts/instance-0/output/build/znc-1.7.5/CMakeFiles/CMakeTmp/CheckSymbolExists.cxx:8:19: error: 'getpassphrase' was not declared in this scope
   return ((int*)(&getpassphrase))[argc];
                   ^~~~~~~~~~~~~
gmake[2]: *** [CMakeFiles/cmTC_835da.dir/CheckSymbolExists.cxx.o] Error 1
gmake[2]: Leaving directory `/usr/lfs/hdd_v1/rc-buildroot-test/scripts/instance-0/output/build/znc-1.7.5/CMakeFiles/CMakeTmp'
gmake[1]: *** [cmTC_835da/fast] Error 2
gmake[1]: Leaving directory `/usr/lfs/hdd_v1/rc-buildroot-test/scripts/instance-0/output/build/znc-1.7.5/CMakeFiles/CMakeTmp'

File /usr/lfs/hdd_v1/rc-buildroot-test/scripts/instance-0/output/build/znc-1.7.5/CMakeFiles/CMakeTmp/CheckSymbolExists.cxx:
/* */
#include <stdlib.h>

int main(int argc, char** argv)
{
  (void)argv;
#ifndef getpassphrase
  return ((int*)(&getpassphrase))[argc];
#else
  (void)argc;
  return 0;
#endif
}