Undefined references to thread when building tensorflow examples

[michaelgruner]

This is using the r2inference-ubuntu-16.04:v0.3.0 container

make[4]: Entering directory '/root/r2inference-leak/examples/r2i/tensorflow'
/bin/bash ../../../libtool  --tag=CXX   --mode=link g++ -std=gnu++11 -Werror -Wall -O0 -ggdb3   -I../common/ -I/usr/local/include/tensorflow/lite/tools/make/downloads/flatbuffers/include -O0 -ggdb3   ../../../r2i/libr2inference-0.0.la  -o inception inception.o
libtool: link: g++ -std=gnu++11 -Werror -Wall -O0 -ggdb3 -I../common/ -I/usr/local/include/tensorflow/lite/tools/make/downloads/flatbuffers/include -O0 -ggdb3 -o .libs/inception inception.o  ../../../r2i/.libs/libr2inference-0.0.so -pthread
../../../r2i/.libs/libr2inference-0.0.so: undefined reference to `typeinfo for std::thread::_State'
../../../r2i/.libs/libr2inference-0.0.so: undefined reference to `std::thread::_M_start_thread(std::unique_ptr<std::thread::_State, std::default_delete<std::thread::_State> >, void (*)())'
../../../r2i/.libs/libr2inference-0.0.so: undefined reference to `std::thread::_State::~_State()'
collect2: error: ld returned 1 exit status
Makefile:445: recipe for target 'inception' failed