fix sdk target with absolute OUT_DIR
fix sdk target with absolute OUT_DIR

Add / to atree's search path.

since I459a3b13 OUT_DIR is absolute. atree uses these variables and
due to "-I ." tries to resolve these paths as relative paths.

Change-Id: Ic9fbc84acdd9f438dfc813f6496e2c5e0d761976

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