cmake output:
-- Looking for include file pthread.h
-- Looking for include file pthread.h - found
-- Looking for pthread_create
-- Looking for pthread_create - not found
-- Looking for pthread_create in pthreads
-- Looking for pthread_create in pthreads - not found
-- Looking for pthread_create in pthread
-- Looking for pthread_create in pthread - found

CMakeError.log
Determining if the pthread_create exist failed with the following output:
Change Dir: /home/nikno/tc/TrinityCore/builddir/CMakeFiles/CMakeTmp

Run Build Command:/usr/bin/make "cmTryCompileExec462969063/fast"
/usr/bin/make -f CMakeFiles/cmTryCompileExec462969063.dir/build.make CMakeFiles/cmTryCompileExec462969063.dir/build
make[1]: Entering directory `/home/nikno/tc/TrinityCore/builddir/CMakeFiles/CMakeTmp'
/usr/local/bin/cmake -E cmake_progress_report /home/nikno/tc/TrinityCore/builddir/CMakeFiles/CMakeTmp/CMakeFiles 1
Building C object CMakeFiles/cmTryCompileExec462969063.dir/CheckSymbolExists.c.o
/usr/bin/cc   -std=gnu99 -W -Wall -Wextra -Winit-self -Winvalid-pch -Wfatal-errors    -o CMakeFiles/cmTryCompileExec462969063.dir/CheckSymbolExists.c.o   -c /home/nikno/tc/TrinityCore/builddir/CMakeFiles/CMakeTmp/CheckSymbolExists.c
Linking C executable cmTryCompileExec462969063
/usr/local/bin/cmake -E cmake_link_script CMakeFiles/cmTryCompileExec462969063.dir/link.txt --verbose=1
/usr/bin/cc   -std=gnu99 -W -Wall -Wextra -Winit-self -Winvalid-pch -Wfatal-errors     CMakeFiles/cmTryCompileExec462969063.dir/CheckSymbolExists.c.o  -o cmTryCompileExec462969063 -rdynamic
CMakeFiles/cmTryCompileExec462969063.dir/CheckSymbolExists.c.o: In function `main':
CheckSymbolExists.c:(.text+0x16): undefined reference to `pthread_create'
collect2: error: ld returned 1 exit status
make[1]: *** [cmTryCompileExec462969063] Error 1
make[1]: Leaving directory `/home/nikno/tc/TrinityCore/builddir/CMakeFiles/CMakeTmp'
make: *** [cmTryCompileExec462969063/fast] Error 2

File /home/nikno/tc/TrinityCore/builddir/CMakeFiles/CMakeTmp/CheckSymbolExists.c:
/* */
#include <pthread.h>

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

Determining if the function pthread_create exists in the pthreads failed with the following output:
Change Dir: /home/nikno/tc/TrinityCore/builddir/CMakeFiles/CMakeTmp

Run Build Command:/usr/bin/make "cmTryCompileExec4162611473/fast"
/usr/bin/make -f CMakeFiles/cmTryCompileExec4162611473.dir/build.make CMakeFiles/cmTryCompileExec4162611473.dir/build
make[1]: Entering directory `/home/nikno/tc/TrinityCore/builddir/CMakeFiles/CMakeTmp'
/usr/local/bin/cmake -E cmake_progress_report /home/nikno/tc/TrinityCore/builddir/CMakeFiles/CMakeTmp/CMakeFiles 1
Building C object CMakeFiles/cmTryCompileExec4162611473.dir/CheckFunctionExists.c.o
/usr/bin/cc   -std=gnu99 -W -Wall -Wextra -Winit-self -Winvalid-pch -Wfatal-errors -DCHECK_FUNCTION_EXISTS=pthread_create   -o CMakeFiles/cmTryCompileExec4162611473.dir/CheckFunctionExists.c.o   -c /usr/local/share/cmake-2.8/Modules/CheckFunctionExists.c
Linking C executable cmTryCompileExec4162611473
/usr/local/bin/cmake -E cmake_link_script CMakeFiles/cmTryCompileExec4162611473.dir/link.txt --verbose=1
/usr/bin/cc   -std=gnu99 -W -Wall -Wextra -Winit-self -Winvalid-pch -Wfatal-errors -DCHECK_FUNCTION_EXISTS=pthread_create    CMakeFiles/cmTryCompileExec4162611473.dir/CheckFunctionExists.c.o  -o cmTryCompileExec4162611473 -rdynamic -lpthreads
/usr/bin/ld: cannot find -lpthreads
collect2: error: ld returned 1 exit status
make[1]: *** [cmTryCompileExec4162611473] Error 1
make[1]: Leaving directory `/home/nikno/tc/TrinityCore/builddir/CMakeFiles/CMakeTmp'
make: *** [cmTryCompileExec4162611473/fast] Error 2