Fix gemm_kernel crashed in docker image

[gangliao]

询问过了Openblas的人了，目前docker image之所以会出现gemm_kernel使用非法硬件指令，是因为之前我在写cmake build的时候，没有把指令集动态切换的选项加上。

That cmake file would indeed build an OpenBLAS that is tailored to the cpu of the build system. Please add "DYNAMIC_ARCH=1" to the build flags to get a (bigger) libopenblas.a with support for a range of x86 cpus (and builtin code to select the most appropriate one at runtime), or if library size is a concern
build for the oldest, least sophisticated cpu you expect to encounter, e.g. TARGET=NEHALEM.

[helinwang]

LGTM++