Fix OpenMP builds on Unix

Author: ismail

CMakeLists.txt

@@ -120,7 +120,7 @@ endif()
 
 if (OPENMP_BUILD)
     if (CLANG)
-        set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Xclang -fopenmp")
+        set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -fopenmp")
     else(MSVC)
         set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} /openmp")
     endif()
@@ -427,6 +427,10 @@ if (HAVE_TIFFIO_H)
     target_link_libraries(tesseract tiff)
 endif()
 
+if (OPENMP_BUILD AND UNIX)
+target_link_libraries           (tesseract pthread)
+endif()
+
 ########################################
 
 if (BUILD_TESTS AND EXISTS ${CMAKE_CURRENT_SOURCE_DIR}/googletest/CMakeLists.txt)