CMakeLists.txt

cmake_minimum_required (VERSION 2.8.12)

project (test CXX C)

set(THREADS_PREFER_PTHREAD_FLAG ON)
find_package(Threads REQUIRED)

add_executable(zzzzzz zzzzzz.cc)
target_link_libraries(zzzzzz Threads::Threads)

gistfile1.txt

$ CC=gcc-8 CXX=g++-8 CFLAGS="-fsanitize=address " CXXFLAGS="-fsanitize=address " cmake  ../ && make VERBOSE=1 zzzzzz
/usr/bin/g++-8    -fsanitize=address   -o CMakeFiles/zzzzzz.dir/zzzzzz.cc.o -c /home/lebedevri/cmake-bug-pthread/zzzzzz.cc
[100%] Linking CXX executable zzzzzz
/usr/bin/cmake -E cmake_link_script CMakeFiles/zzzzzz.dir/link.txt --verbose=1
/usr/bin/g++-8  -fsanitize=address  -rdynamic CMakeFiles/zzzzzz.dir/zzzzzz.cc.o  -o zzzzzz 

$ CC=gcc-8 CXX=g++-8 cmake  ../ && make VERBOSE=1 zzzzzz
[ 50%] Building CXX object CMakeFiles/zzzzzz.dir/zzzzzz.cc.o
/usr/bin/g++-8    -pipe   -pthread -o CMakeFiles/zzzzzz.dir/zzzzzz.cc.o -c /home/lebedevri/cmake-bug-pthread/zzzzzz.cc
[100%] Linking CXX executable zzzzzz
/usr/bin/cmake -E cmake_link_script CMakeFiles/zzzzzz.dir/link.txt --verbose=1
/usr/bin/g++-8  -pipe  -rdynamic CMakeFiles/zzzzzz.dir/zzzzzz.cc.o  -o zzzzzz -pthread 

zzzzzz.cc

int main() {return 0;}