add bc dependence

[daixiang0]

Signed-off-by: Xiang Dai 764524258@qq.com

Without bc, build would fail:

...
Copying locales file to backend dist dirs

Copying Dockerfile to backend dist dirs
./aio/scripts/build.sh: line 126: bc: command not found
npm ERR! code ELIFECYCLE
npm ERR! syscall spawn
npm ERR! file sh
npm ERR! errno ENOENT
npm ERR! kubernetes-dashboard@2.0.0-beta4 build: ./aio/scripts/build.sh
npm ERR! spawn ENOENT
npm ERR! 
npm ERR! Failed at the kubernetes-dashboard@2.0.0-beta4 build script.
npm ERR! This is probably not a problem with npm. There is likely additional logging output above.

npm ERR! A complete log of this run can be found in:
npm ERR! /root/.npm/_logs/2020-01-20T09_59_52_893Z-debug.log

[codecov]

Codecov Report

Merging #4816 into master will increase coverage by 0.01%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #4816      +/-   ##
==========================================
+ Coverage   45.42%   45.43%   +0.01%     
==========================================
  Files         214      214              
  Lines        9977     9977              
  Branches       94       94              
==========================================
+ Hits         4532     4533       +1     
+ Misses       5181     5180       -1     
  Partials      264      264

Impacted Files	Coverage Δ
...p/backend/integration/metric/common/aggregation.go	90.9% <0%> (+1.81%)	⬆️

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[shu-mutou]

/lgtm
/approve

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: daixiang0, shu-mutou

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