Fix CMake build when Qt5 is partially found

Thanks kerio for report

test/CMakeLists.txt

@@ -67,10 +67,19 @@ target_include_directories(unittest_bin PRIVATE
 	"${GMOCK_ROOT}" "${GMOCK_ROOT}/include")
 add_custom_target(unittest COMMAND unittest_bin)
 
-find_package(Qt5Network 5.4 QUIET HINTS ${brew_qt5})
-if(Qt5Network_FOUND)
-	find_package_message(qt "Found Qt ${Qt5Network_VERSION}"
-		"1;${Qt5Network_VERSION}")
+try_compile(qt5_findable
+	"${PROJECT_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/qt5check"
+	"${PROJECT_SOURCE_DIR}/cmake/qt5check" qt5check
+	CMAKE_FLAGS "-DQt5_HINTS=${brew_qt5}"
+	OUTPUT_VARIABLE _Qt5Check_tryout)
+if(qt5_findable)
+	file(APPEND
+		"${PROJECT_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/CMakeOutput.log"
+		"Output of Qt5 check:\n${_Qt5Check_tryout}\n")
+	string(REGEX REPLACE ".*QT5_VERSION_BEGIN:" "" qt5_version
+		"${_Qt5Check_tryout}")
+	string(REGEX REPLACE ":QT5_VERSION_END.*" "" qt5_version "${qt5_version}")
+	find_package_message(qt "Found Qt ${qt5_version}" "1;${qt5_version}")
 	# Use different compiler flags, because Qt fails with sanitizers,
 	# and we don't need sanitizers to test the test itself anyway.
 	externalproject_add(inttest_bin
@@ -92,6 +101,9 @@ if(Qt5Network_FOUND)
 		"${CMAKE_CURRENT_BINARY_DIR}/integration/inttest")
 	add_dependencies(inttest inttest_bin)
 else()
+	file(APPEND
+		"${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/CMakeError.log"
+		"Error in Qt5 check:\n${_Qt5Check_tryout}\n")
 	find_package_message(qt
 		"Qt >= 5.4 not found, integration testing will be disabled" "0")
 endif()

test/integration/CMakeLists.txt

@@ -24,7 +24,7 @@ set(CMAKE_THREAD_PREFER_PTHREAD true)
 set(THREADS_PREFER_PTHREAD_FLAG true)
 find_package(Threads REQUIRED)
 
-find_package(Qt5Network 5.4 HINTS ${Qt5_HINTS})
+find_package(Qt5Network 5.4 REQUIRED HINTS ${Qt5_HINTS})
 
 # Force the simple internal regex engine to get consistent behavior on all
 # platforms. See