droid_surfaceflingerlink.cpp: fix compiling error for android5.0

update the version check for android 5.0 in file droid_surfaceflingerlink.cpp

Change-Id: Iee3f294dfd4951d4b2fff9cc2afeebc0d2d24802
Signed-off-by: Yongqin Liu <yongqin.liu@linaro.org>
Android.mk: fix problem when compile with 64bit version

TARGET_CC should not be specified in the Android.mk file
directly since it would be different file for 64bit and 32 bit.
change to use the default gcc target file

and mv the -std=c99 to LOCAL_CFLAGS variable.

Change-Id: I9ca3d714963493841ff7eaaae69a33b881fd1727
Signed-off-by: Yongqin Liu <yongqin.liu@linaro.org>