Update CMakeLists.txt

[apg360]

Good day,

While compiling in Linux Manjaro 20, running kernel 5.8.16-2.

Either make or ninja, I will face this error :

[user@manjaro20-pc build]$ ninja
[99/99] Linking CXX executable c2c/c2c
FAILED: c2c/c2c 
: && clang++ -O3 -DNDEBUG -rdynamic c2c/CMakeFiles/c2c.dir/main.cpp.o -o c2c/c2c  c2c/libc2core.a  -L/usr/lib  -lLLVM-10  -ltinfo && :
/usr/bin/ld: c2c/libc2core.a(IRGenerator.cpp.o): undefined reference to symbol 'pthread_create@@GLIBC_2.2.5'
/usr/bin/ld: /usr/lib/../lib/libpthread.so.0: error adding symbols: DSO missing from command line
clang-10: error: linker command failed with exit code 1 (use -v to see invocation)
ninja: build stopped: subcommand failed.
[user@manjaro20-pc build]$

Found the solution here : https://stackoverflow.com/questions/34143265/undefined-reference-to-symbol-pthread-createglibc-2-2-5

set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -pthread")

Best regards

[bvdberg]

thx, merged!