test: Add more logging to TCP connection constructor.

Also add more asserts to the test so we don't do UB.

.github/scripts/cmake-freebsd

@@ -42,6 +42,7 @@ RUN "cmake -B_build -Hc-toxcore \
   -DCMAKE_EXE_LINKER_FLAGS='$LD_FLAGS' \
   -DCMAKE_SHARED_LINKER_FLAGS='$LD_FLAGS' \
   -DCMAKE_INSTALL_PREFIX:PATH='_install' \
+  -DENABLE_SHARED=OFF \
   -DMIN_LOGGER_LEVEL=TRACE \
   -DMUST_BUILD_TOXAV=ON \
   -DNON_HERMETIC_TESTS=ON \