Determining if the PHYSFS_getPrefDir exist failed with the following output:
Change Dir: /usr/lfs/hdd_v1/rc-buildroot-test/scripts/instance-2/output/build/supertux-0.6.0/CMakeFiles/CMakeTmp

Run Build Command(s):/usr/bin/gmake cmTC_fe4e9/fast && gmake[1]: Entering directory `/usr/lfs/hdd_v1/rc-buildroot-test/scripts/instance-2/output/build/supertux-0.6.0/CMakeFiles/CMakeTmp'
/usr/bin/gmake -f CMakeFiles/cmTC_fe4e9.dir/build.make CMakeFiles/cmTC_fe4e9.dir/build
gmake[2]: Entering directory `/usr/lfs/hdd_v1/rc-buildroot-test/scripts/instance-2/output/build/supertux-0.6.0/CMakeFiles/CMakeTmp'
Building C object CMakeFiles/cmTC_fe4e9.dir/CheckSymbolExists.c.o
/usr/lfs/hdd_v1/rc-buildroot-test/scripts/instance-2/output/host/bin/x86_64-linux-gcc --sysroot=/usr/lfs/hdd_v1/rc-buildroot-test/scripts/instance-2/output/host/x86_64-buildroot-linux-uclibc/sysroot   -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64 -O2   -DNDEBUG   -o CMakeFiles/cmTC_fe4e9.dir/CheckSymbolExists.c.o   -c /usr/lfs/hdd_v1/rc-buildroot-test/scripts/instance-2/output/build/supertux-0.6.0/CMakeFiles/CMakeTmp/CheckSymbolExists.c
Linking C executable cmTC_fe4e9
/usr/lfs/hdd_v1/rc-buildroot-test/scripts/instance-2/output/host/bin/cmake -E cmake_link_script CMakeFiles/cmTC_fe4e9.dir/link.txt --verbose=1
/usr/lfs/hdd_v1/rc-buildroot-test/scripts/instance-2/output/host/bin/x86_64-linux-gcc --sysroot=/usr/lfs/hdd_v1/rc-buildroot-test/scripts/instance-2/output/host/x86_64-buildroot-linux-uclibc/sysroot -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64 -O2   -DNDEBUG    CMakeFiles/cmTC_fe4e9.dir/CheckSymbolExists.c.o  -o cmTC_fe4e9 
/usr/lfs/hdd_v1/rc-buildroot-test/scripts/instance-2/output/host/opt/ext-toolchain/bin/../lib/gcc/x86_64-buildroot-linux-uclibc/8.3.0/../../../../x86_64-buildroot-linux-uclibc/bin/ld: CMakeFiles/cmTC_fe4e9.dir/CheckSymbolExists.c.o: in function `main':
CheckSymbolExists.c:(.text.startup+0x3): undefined reference to `PHYSFS_getPrefDir'
collect2: error: ld returned 1 exit status
gmake[2]: *** [cmTC_fe4e9] Error 1
gmake[2]: Leaving directory `/usr/lfs/hdd_v1/rc-buildroot-test/scripts/instance-2/output/build/supertux-0.6.0/CMakeFiles/CMakeTmp'
gmake[1]: *** [cmTC_fe4e9/fast] Error 2
gmake[1]: Leaving directory `/usr/lfs/hdd_v1/rc-buildroot-test/scripts/instance-2/output/build/supertux-0.6.0/CMakeFiles/CMakeTmp'


File /usr/lfs/hdd_v1/rc-buildroot-test/scripts/instance-2/output/build/supertux-0.6.0/CMakeFiles/CMakeTmp/CheckSymbolExists.c:
/* */
#include </usr/lfs/hdd_v1/rc-buildroot-test/scripts/instance-2/output/host/x86_64-buildroot-linux-uclibc/sysroot/usr/include/physfs.h>

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

Performing C++ SOURCE FILE Test HAVE_ICONV_CONST failed with the following output:
Change Dir: /usr/lfs/hdd_v1/rc-buildroot-test/scripts/instance-2/output/build/supertux-0.6.0/CMakeFiles/CMakeTmp

Run Build Command(s):/usr/bin/gmake cmTC_5464c/fast && gmake[1]: Entering directory `/usr/lfs/hdd_v1/rc-buildroot-test/scripts/instance-2/output/build/supertux-0.6.0/CMakeFiles/CMakeTmp'
/usr/bin/gmake -f CMakeFiles/cmTC_5464c.dir/build.make CMakeFiles/cmTC_5464c.dir/build
gmake[2]: Entering directory `/usr/lfs/hdd_v1/rc-buildroot-test/scripts/instance-2/output/build/supertux-0.6.0/CMakeFiles/CMakeTmp'
Building CXX object CMakeFiles/cmTC_5464c.dir/src.cxx.o
/usr/lfs/hdd_v1/rc-buildroot-test/scripts/instance-2/output/host/bin/x86_64-linux-g++ --sysroot=/usr/lfs/hdd_v1/rc-buildroot-test/scripts/instance-2/output/host/x86_64-buildroot-linux-uclibc/sysroot    -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64 -O2 -DHAVE_ICONV_CONST  -DNDEBUG   -o CMakeFiles/cmTC_5464c.dir/src.cxx.o -c /usr/lfs/hdd_v1/rc-buildroot-test/scripts/instance-2/output/build/supertux-0.6.0/CMakeFiles/CMakeTmp/src.cxx
/usr/lfs/hdd_v1/rc-buildroot-test/scripts/instance-2/output/build/supertux-0.6.0/CMakeFiles/CMakeTmp/src.cxx:4:9: error: ambiguating new declaration of 'double iconv(iconv_t, char**, size_t*, char**, size_t*)'
  double iconv(iconv_t cd,  char **inbuf, size_t *inbytesleft, char **outbuf, size_t *outbytesleft);
         ^~~~~
In file included from /usr/lfs/hdd_v1/rc-buildroot-test/scripts/instance-2/output/build/supertux-0.6.0/CMakeFiles/CMakeTmp/src.cxx:2:
/usr/lfs/hdd_v1/rc-buildroot-test/scripts/instance-2/output/host/x86_64-buildroot-linux-uclibc/sysroot/usr/include/iconv.h:20:1: note: old declaration 'size_t iconv(iconv_t, char**, size_t*, char**, size_t*)'
 iconv(iconv_t cd, char **inbuf, size_t *inbytesleft,
 ^~~~~
gmake[2]: *** [CMakeFiles/cmTC_5464c.dir/src.cxx.o] Error 1
gmake[2]: Leaving directory `/usr/lfs/hdd_v1/rc-buildroot-test/scripts/instance-2/output/build/supertux-0.6.0/CMakeFiles/CMakeTmp'
gmake[1]: *** [cmTC_5464c/fast] Error 2
gmake[1]: Leaving directory `/usr/lfs/hdd_v1/rc-buildroot-test/scripts/instance-2/output/build/supertux-0.6.0/CMakeFiles/CMakeTmp'


Source file was:

	#include <iconv.h>
	// this declaration will fail when there already exists a non const char** version which returns size_t
	double iconv(iconv_t cd,  char **inbuf, size_t *inbytesleft, char **outbuf, size_t *outbytesleft);
	int main() { return 0; }