add json lib stuff. not sure if it was needed. but when compiling a new image...

add json lib stuff. not sure if it was needed. but when compiling a new image for xiaomi_mi-router-4c, I had an error. after deleting working dir and installing those libs, it was compiling
Status Name Job ID Coverage
  Init
canceled docker:init #24233
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  Build
canceled docker:ar71xx.generic.lowmem #24235
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canceled docker:ar71xx.tiny.lowmem #24234
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canceled docker:ath79 #24239
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canceled docker:ipq40xx #24240
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canceled docker:lantiq #24238
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canceled docker:mediatek #24243
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canceled docker:mpc85xx #24242
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canceled docker:ramips #24237
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canceled docker:sunxi #24241
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canceled docker:x86.64.offloader #24236
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