FastSignals: Fix stress tests.

src/3rdParty/FastSignals/tests/libfastsignals_stress_tests/CMakeLists.txt

@@ -1,2 +1,4 @@
 
 custom_add_test_from_dir(libfastsignals_stress_tests libfastsignals)
+custom_enable_cxx17(libfastsignals_stress_tests)
+target_include_directories(libfastsignals_stress_tests PRIVATE "${CMAKE_SOURCE_DIR}/tests")

src/3rdParty/FastSignals/tests/libfastsignals_stress_tests/signal_stress_tests.cpp

@@ -4,6 +4,7 @@
 #include <mutex>
 #include <random>
 #include <vector>
+#include <thread>
 
 using namespace fastsignals;