Build failure on Ubuntu 18.04 with gcc 7.4.0 (default)

[alex-luxonis]

The final link step is failing with this error:

depthai-api/host/py_module/build$ make
[ 20%] Built target nlohmann_json_schema_validator
[ 24%] Linking CXX shared module depthai.cpython-36m-x86_64-linux-gnu.so
/usr/bin/ld: /tmp/ccMFU1de.ltrans0.ltrans.o: relocation R_X86_64_PC32 against symbol `_ZNSt14__shared_countILN9__gnu_cxx12_Lock_policyE2EEC1Ev' can not be used when making a shared object; recompile with -fPIC
/usr/bin/ld: final link failed: Bad value
collect2: error: ld returned 1 exit status
CMakeFiles/depthai.dir/build.make:563: recipe for target 'depthai.cpython-36m-x86_64-linux-gnu.so' failed
make[2]: *** [depthai.cpython-36m-x86_64-linux-gnu.so] Error 1
CMakeFiles/Makefile2:67: recipe for target 'CMakeFiles/depthai.dir/all' failed
make[1]: *** [CMakeFiles/depthai.dir/all] Error 2
Makefile:129: recipe for target 'all' failed
make: *** [all] Error 2

[alex-luxonis]

Compiler version when the failure occurred:
g++ --version

g++ (Ubuntu 7.4.0-1ubuntu1~18.04.1) 7.4.0

[alex-luxonis]

Upgrading to gcc/g++ 8 seems to be a solution/workaround for this issue:

sudo apt install g++-8
sudo update-alternatives --install /usr/bin/g++ g++ /usr/bin/g++-8 70
sudo update-alternatives --install /usr/bin/gcc gcc /usr/bin/gcc-8 70

g++ --version

g++ (Ubuntu 8.3.0-26ubuntu1~18.04) 8.3.0

Will add this info in README.md as well.