Fix OpenMP build issue with perf_lib target (#198)

Author: aobolensk

CMakeLists.txt

@@ -30,6 +30,10 @@ add_subdirectory(3rdparty)
 
 include(cmake/opencv_config.cmake)
 
+if (NOT WIN32)
+    find_package(OpenMP REQUIRED)
+endif()
+
 if (NOT WIN32)
     set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Wall -Wextra -Werror")
     set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wall -Wextra -Werror")

src/perf/CMakeLists.txt

@@ -1,2 +1,5 @@
 file(GLOB_RECURSE perf_src *.cpp)
 add_library(perf_lib STATIC "${PERF_HEADERS}" "${perf_src}")
+if (NOT WIN32)
+    target_link_libraries(perf_lib PUBLIC OpenMP::OpenMP_CXX)
+endif()

test/CMakeLists.txt

@@ -1,9 +1,5 @@
 file(GLOB_RECURSE TEST_SRC_FILES ${CMAKE_CURRENT_SOURCE_DIR}/*.cpp)
 
-if (NOT WIN32)
-    find_package(OpenMP REQUIRED)
-endif()
-
 add_executable(run_test ${TEST_SRC_FILES})
 if (NOT WIN32)
     target_link_libraries(run_test PUBLIC OpenMP::OpenMP_CXX)