title: error during compilation gr-gsm for GNU Radio 3.8
body: <p>I'm trying to compile gr-gsm ( <a href="https://github.com/ptrkrysik/gr-gsm" rel="nofollow noreferrer">https://github.com/ptrkrysik/gr-gsm</a> ) project. While running cmake I'm occuring following error:</p>
  
  <pre><code>.
  .
  .
  Building C object CMakeFiles/cmTC_5223d.dir/CheckFunctionExists.c.o
  /usr/bin/cc   -DCHECK_FUNCTION_EXISTS=pthread_create   -o CMakeFiles/cmTC_5223d.dir/CheckFunctionExists.c.o   -c /usr/share/cmake-3.16/Modules/CheckFunctionExists.c
  Linking C executable cmTC_5223d
  /usr/bin/cmake -E cmake_link_script CMakeFiles/cmTC_5223d.dir/link.txt --verbose=1
  /usr/bin/cc  -DCHECK_FUNCTION_EXISTS=pthread_create    -rdynamic CMakeFiles/cmTC_5223d.dir   /CheckFunctionExists.c.o  -o cmTC_5223d  -lpthreads 
  /usr/bin/ld: cannot find -lpthreads
  collect2: error: ld returned 1 exit status
  make[1]: *** [CMakeFiles/cmTC_5223d.dir/build.make:87: cmTC_5223d] Błąd 1
  make[1]: Opuszczenie katalogu '/home/notroot/Pobrane/gr-gsm/build/CMakeFiles/CMakeTmp'
  make: *** [Makefile:121: cmTC_5223d/fast] Błąd 2
  </code></pre>
  
  <p>and after running <strong>/usr/bin/cc -lpthreads</strong> command I also occur this error:</p>
  
  <pre><code>/usr/bin/ld: cannot find -lpthreads
  collect2: error: ld returned 1 exit status
  </code></pre>
  
  <p>but not after running <strong>/usr/bin/cc -lpthread</strong> command that produces this output:</p>
  
  <pre><code>/usr/bin/ld: /usr/lib/gcc/x86_64-pc-linux-gnu/9.2.0/../../../../lib/Scrt1.o: in function `_start':
  (.text+0x24): undefined reference to `main'
  collect2: error: ld returned 1 exit status
  </code></pre>
  
  <p>I managed to replace all <strong>-lpthreads</strong> with <strong>-lpthread</strong> flag with <strong>grep -irl "lpthreads" ./* | xargs sed -i 's/lpthreads/lpthread/g'</strong> command. After running it I see following error:</p>
  
  <pre><code>Building C object CMakeFiles/cmTC_5223d.dir/CheckFunctionExists.c.o
  /usr/bin/cc   -DCHECK_FUNCTION_EXISTS=pthread_create   -o CMakeFiles/cmTC_5223d.dir/CheckFunctionExists.c.o   -c /usr/share/cmake-3.16/Modules/CheckFunctionExists.c
  Linking C executable cmTC_5223d
  /usr/bin/cmake -E cmake_link_script CMakeFiles/cmTC_5223d.dir/link.txt --verbose=1
  /usr/bin/cc  -DCHECK_FUNCTION_EXISTS=pthread_create    -rdynamic CMakeFiles/cmTC_5223d.dir/CheckFunctionExists.c.o  -o cmTC_5223d  -lpthread 
  /usr/bin/ld: cannot find -lpthread
  collect2: error: ld returned 1 exit status
  make[1]: *** [CMakeFiles/cmTC_5223d.dir/build.make:87: cmTC_5223d] Błąd 1
  make[1]: Opuszczenie katalogu '/home/notroot/Pobrane/gr-gsm/build/CMakeFiles/CMakeTmp'
  make: *** [Makefile:121: cmTC_5223d/fast] Błąd 2
  </code></pre>
  
  <p>but while running without cmake ld an find lpthread!</p>