CMake: Remove OpenMP stuff, it's unused and breaks Travis clang build

CMakeLists.txt

@@ -151,19 +151,6 @@ IF(ASSIMP_DOUBLE_PRECISION)
     ADD_DEFINITIONS(-DASSIMP_DOUBLE_PRECISION)
 ENDIF(ASSIMP_DOUBLE_PRECISION)
 
-# Check for OpenMP support
-find_package(OpenMP)
-if (OPENMP_FOUND)
-    SET (CMAKE_C_FLAGS "${CMAKE_C_FLAGS} ${OpenMP_C_FLAGS}")
-    SET (CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${OpenMP_CXX_FLAGS}")
-
-    IF(MSVC)
-        IF(MSVC_VERSION GREATER 1910)
-            SET (CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} /Zc:twoPhase-")
-        ENDIF()
-    ENDIF()
-endif()
-
 CONFIGURE_FILE(
   ${CMAKE_CURRENT_LIST_DIR}/revision.h.in
   ${CMAKE_CURRENT_BINARY_DIR}/revision.h