Determining if the function pthread_create exists in the pthreads failed with the following output:
Change Dir: /home/naourr/work/instance-2/output/build/librtlsdr-v0.5.4/CMakeFiles/CMakeTmp

Run Build Command:"/usr/bin/gmake" "cmTC_a4918/fast"
gmake[1]: Entering directory '/home/naourr/work/instance-2/output/build/librtlsdr-v0.5.4/CMakeFiles/CMakeTmp'
/usr/bin/gmake -f CMakeFiles/cmTC_a4918.dir/build.make CMakeFiles/cmTC_a4918.dir/build
gmake[2]: Entering directory '/home/naourr/work/instance-2/output/build/librtlsdr-v0.5.4/CMakeFiles/CMakeTmp'
Building C object CMakeFiles/cmTC_a4918.dir/CheckFunctionExists.c.o
/home/naourr/work/instance-2/output/host/bin/sh4-linux-gcc --sysroot=/home/naourr/work/instance-2/output/host/sh4-buildroot-linux-uclibc/sysroot   -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64 -Os -static -DCHECK_FUNCTION_EXISTS=pthread_create  -DNDEBUG   -o CMakeFiles/cmTC_a4918.dir/CheckFunctionExists.c.o   -c /usr/share/cmake/Modules/CheckFunctionExists.c
Linking C executable cmTC_a4918
/usr/bin/cmake -E cmake_link_script CMakeFiles/cmTC_a4918.dir/link.txt --verbose=1
/home/naourr/work/instance-2/output/host/bin/sh4-linux-gcc --sysroot=/home/naourr/work/instance-2/output/host/sh4-buildroot-linux-uclibc/sysroot -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64 -Os -static -DCHECK_FUNCTION_EXISTS=pthread_create  -DNDEBUG  -static  -rdynamic CMakeFiles/cmTC_a4918.dir/CheckFunctionExists.c.o  -o cmTC_a4918 -lpthreads /home/naourr/work/instance-2/output/host/sh4-buildroot-linux-uclibc/sysroot/usr/lib/libusb-1.0.a 
/home/naourr/work/instance-2/output/host/opt/ext-toolchain/bin/../lib/gcc/sh4-buildroot-linux-uclibc/6.4.0/../../../../sh4-buildroot-linux-uclibc/bin/ld: cannot find -lpthreads
collect2: error: ld returned 1 exit status
gmake[2]: *** [CMakeFiles/cmTC_a4918.dir/build.make:88: cmTC_a4918] Error 1
gmake[2]: Leaving directory '/home/naourr/work/instance-2/output/build/librtlsdr-v0.5.4/CMakeFiles/CMakeTmp'
gmake[1]: *** [Makefile:126: cmTC_a4918/fast] Error 2
gmake[1]: Leaving directory '/home/naourr/work/instance-2/output/build/librtlsdr-v0.5.4/CMakeFiles/CMakeTmp'