Add clean step for SDK version change.
Add clean step for SDK version change.

Change-Id: I2ea85496af49572115dbbd9a98787b1fd54adc50

see4ri/lolili,xorware/android_build,ND-3500/platform_manifest,hagar006/platform_manifest,xorware/android_build,xorware/android_build,knone1/platform_manifest,xorware/android_build,Hybrid-Power/startsync,RR-msm7x30/platform_manifest,fallouttester/platform_manifest,pranav01/platform_manifest,xorware/android_build