Determining if the strtod_l exist failed with the following output:
Change Dir: /data/buildroot-test/instance-0/output-1/build/fmt-7.1.3/CMakeFiles/CMakeTmp

Run Build Command(s):/usr/bin/make cmTC_2c896/fast && make[1]: Entering directory '/data/buildroot-test/instance-0/output-1/build/fmt-7.1.3/CMakeFiles/CMakeTmp'
/usr/bin/make -f CMakeFiles/cmTC_2c896.dir/build.make CMakeFiles/cmTC_2c896.dir/build
make[2]: Entering directory '/data/buildroot-test/instance-0/output-1/build/fmt-7.1.3/CMakeFiles/CMakeTmp'
Building CXX object CMakeFiles/cmTC_2c896.dir/CheckSymbolExists.cxx.o
/data/buildroot-test/instance-0/output-1/host/bin/powerpc-linux-g++ --sysroot=/data/buildroot-test/instance-0/output-1/host/powerpc-buildroot-linux-uclibc/sysroot    -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64 -Os   -DNDEBUG   -std=gnu++11 -o CMakeFiles/cmTC_2c896.dir/CheckSymbolExists.cxx.o -c /data/buildroot-test/instance-0/output-1/build/fmt-7.1.3/CMakeFiles/CMakeTmp/CheckSymbolExists.cxx
/data/buildroot-test/instance-0/output-1/build/fmt-7.1.3/CMakeFiles/CMakeTmp/CheckSymbolExists.cxx: In function 'int main(int, char**)':
/data/buildroot-test/instance-0/output-1/build/fmt-7.1.3/CMakeFiles/CMakeTmp/CheckSymbolExists.cxx:8:19: error: 'strtod_l' was not declared in this scope
   return ((int*)(&strtod_l))[argc];
                   ^~~~~~~~
/data/buildroot-test/instance-0/output-1/build/fmt-7.1.3/CMakeFiles/CMakeTmp/CheckSymbolExists.cxx:8:19: note: suggested alternative: 'strtoull'
   return ((int*)(&strtod_l))[argc];
                   ^~~~~~~~
                   strtoull
make[2]: *** [CMakeFiles/cmTC_2c896.dir/build.make:66: CMakeFiles/cmTC_2c896.dir/CheckSymbolExists.cxx.o] Error 1
make[2]: Leaving directory '/data/buildroot-test/instance-0/output-1/build/fmt-7.1.3/CMakeFiles/CMakeTmp'
make[1]: *** [Makefile:121: cmTC_2c896/fast] Error 2
make[1]: Leaving directory '/data/buildroot-test/instance-0/output-1/build/fmt-7.1.3/CMakeFiles/CMakeTmp'


File /data/buildroot-test/instance-0/output-1/build/fmt-7.1.3/CMakeFiles/CMakeTmp/CheckSymbolExists.cxx:
/* */
#include <stdlib.h>

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