openmp's problem on android platform(omp dynamic error)

[flyinskyin2013]

On android platform, when I use ncnn to run two networks in a multi-thread program，I get the following error.

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Some details（Stack trace）:
::omp_get_dynamic()
_kmp_entry_thread()
::kmp_get_global_thread_id_reg()
_kmp_do_serail_initialize()
_kmp_register_library_startup()
::_kmp_msg(xxxxxxxxx)
::_kmp_abort_process()

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Temporary solution：
You can do it in a multi-process program.

[nihui]

the latest code remove these calls in Extractor routine, please verify if it still eats your cat.