issue related to cmake and openmp - c++

Question

I am trying to compile a program on QT creator with cmake. The code(its not my code, I am using it to test something) uses openMP. in my cmake file I have:
`enter code here`project(dbscan_try)
cmake_minimum_required(VERSION 2.8)
aux_source_directory(. SRC_LIST)
SET(CMAKE_CXX_FLAGS "{CMAKE_CXX_FLAGS} -std=c++11 -Wall -fPIC -pedantic -fopenmp -mtune=corei7-avx")
set(Boost_USE_STATIC_LIBS OFF) set(Boost_USE_MULTITHREADED ON) set(Boost_USE_STATIC_RUNTIME OFF) add_definitions(-DBOOST_UBLAS_NDEBUG) add_definitions("-std=c++11") add_definitions("-fopenmp")
add_definitions("-lgomp")
OPTION (USE_OpenMP "Use OpenMP" ON)
find_package(OpenMP)
if (OPENMP_FOUND)
message("OPENMP FOUND")
set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} ${OpenMP_C_FLAGS}")
set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${OpenMP_CXX_FLAGS}")
# set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} ${OpenMP_EXE_LINKER_FLAGS}")
endif()
set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++11 -fopenmp")
find_package(PCL REQUIRED COMPONENTS) include_directories(${PCL_INCLUDE_DIRS} ) link_directories(${PCL_LIBRARY_DIRS}) add_definitions(${PCL_DEFINITIONS})
include_directories({/home/raman/Work/dbscan_try})
set(project_SOURCES
/home/raman/Work/cplusplus_projects/dbscan_try/main.cpp
/home/raman/Work/cplusplus_projects/dbscan_try/dbscan.cpp )
set(project_HEADERS
/home/raman/Work/cplusplus_projects/dbscan_try/dbscan.h)
set(OpenCV_INCLUDE_DIRS "${OpenCV_INSTALL_PATH}/include/opencv;${OpenCV_INSTALL_PATH}/include")
find_package(OpenCV 3.1.0 REQUIRED COMPONENTS) include_directories(-L/usr/local/lib -lopencv_core -lopencv_highgui -lopencv_imgcodecs -lopencv_saliency -lboost_system -lopencv_contrib) set( CMAKE_CXX_FLAGS "-g -Wall")
add_executable(${PROJECT_NAME} ${project_SOURCES})
target_link_libraries(dbscan_try ${PCL_LIBRARIES} ${OpenCV_LIBS} )
However, I am getting errors such as:
/home/raman/Work/cplusplus_projects/dbscan_try/dbscan.cpp:88: error: undefined reference to omp_set_num_threads'
/home/raman/Work/cplusplus_projects/dbscan_try/dbscan.cpp:89: error: undefined reference toGOMP_parallel_start'
etc.
I am new to C++ and cmake so I am not sure if I am doing somethign wrong here. I seem to have followed what other suggestions here mentioned and it worked for them.