Simplify and unify TBB build (#631)

Use built-in "TBB_STRICT" variable instead of manual suppressing all
warnings

Author: aobolensk

cmake/onetbb.cmake

@@ -22,11 +22,10 @@ if(NOT ENABLE_SYSTEM_TBB)
                -DCMAKE_CXX_COMPILER=${CMAKE_CXX_COMPILER}
                -DCMAKE_C_COMPILER_LAUNCHER=${CMAKE_C_COMPILER_LAUNCHER}
                -DCMAKE_CXX_COMPILER_LAUNCHER=${CMAKE_CXX_COMPILER_LAUNCHER}
-               -DCMAKE_C_FLAGS=-w
-               -DCMAKE_CXX_FLAGS=-w
                -DCMAKE_CXX_STANDARD=${CMAKE_CXX_STANDARD}
                -DCMAKE_CXX_STANDARD_REQUIRED=ON
                -DCMAKE_BUILD_TYPE=${CMAKE_BUILD_TYPE}
+               -DTBB_STRICT=OFF
                -DTBB_TEST=OFF
     BUILD_COMMAND
       "${CMAKE_COMMAND}" --build "${CMAKE_CURRENT_BINARY_DIR}/ppc_onetbb/build"