os/compression/compress_read.c : Declare decompression related global variables as static
os/compression/compress_read.c : Declare decompression related global variables as static

- Variables for compression header and decompression buffers are used only in this
  file. So declaring them as static.

Signed-off-by: Amandeep Chauhan <37755504c51ffa7243265501fdc704ed5e783aaa@samsung.com>

Samsung/TizenRT,junmin-kim/TizenRT,jeongarmy/TizenRT,junmin-kim/TizenRT,Samsung/TizenRT,jeongarmy/TizenRT,sunghan-chang/TizenRT,davidfather/TizenRT,junmin-kim/TizenRT,chanijjani/TizenRT,davidfather/TizenRT,an4967/TizenRT,jeongarmy/TizenRT,jsdosa/TizenRT,pillip8282/TizenRT,an4967/TizenRT,jeongchanKim/TizenRT,sunghan-chang/TizenRT,chanijjani/TizenRT,Samsung/TizenRT,junmin-kim/TizenRT,sunghan-chang/TizenRT,sunghan-chang/TizenRT,davidfather/TizenRT,an4967/TizenRT,jeongchanKim/TizenRT,jeongchanKim/TizenRT,chanijjani/TizenRT,sunghan-chang/TizenRT,junmin-kim/TizenRT,an4967/TizenRT,Samsung/TizenRT,pillip8282/TizenRT,pillip8282/TizenRT,Samsung/TizenRT,jsdosa/TizenRT,davidfather/TizenRT,jeongchanKim/TizenRT,chanijjani/TizenRT,an4967/TizenRT,jsdosa/TizenRT,pillip8282/TizenRT,jeongchanKim/TizenRT,jeongarmy/TizenRT,Samsung/TizenRT,jsdosa/TizenRT,jeongarmy/TizenRT,an4967/TizenRT,junmin-kim/TizenRT,jeongarmy/TizenRT,sunghan-chang/TizenRT,Samsung/TizenRT,an4967/TizenRT,davidfather/TizenRT,pillip8282/TizenRT,chanijjani/TizenRT,chanijjani/TizenRT,davidfather/TizenRT,jsdosa/TizenRT,jeongchanKim/TizenRT,pillip8282/TizenRT,junmin-kim/TizenRT,jsdosa/TizenRT,jeongchanKim/TizenRT,davidfather/TizenRT,jeongarmy/TizenRT,chanijjani/TizenRT,sunghan-chang/TizenRT,jsdosa/TizenRT,pillip8282/TizenRT