Allow flashing a squashfs system image

Change-Id: Ic51d11274784a8d2e9d57d5f0b821ebc89680e5a
Signed-off-by: Mohamad Ayyash <mkayyash@google.com>
diff --git a/core/config.mk b/core/config.mk
index ecc8044..e8b6504 100644
--- a/core/config.mk
+++ b/core/config.mk
@@ -398,6 +398,13 @@
 FS_GET_STATS := $(HOST_OUT_EXECUTABLES)/fs_get_stats$(HOST_EXECUTABLE_SUFFIX)
 MAKE_EXT4FS := $(HOST_OUT_EXECUTABLES)/make_ext4fs$(HOST_EXECUTABLE_SUFFIX)
 MKEXTUSERIMG := $(HOST_OUT_EXECUTABLES)/mkuserimg.sh
+ifeq ($(HOST_OS),linux)
+MAKE_SQUASHFS := $(HOST_OUT_EXECUTABLES)/mksquashfs$(HOST_EXECUTABLE_SUFFIX)
+MKSQUASHFSUSERIMG := $(HOST_OUT_EXECUTABLES)/mksquashfsimage.sh
+else
+MAKE_SQUASHFS :=
+MKSQUASHFSUSERIMG :=
+endif
 MAKE_F2FS := $(HOST_OUT_EXECUTABLES)/make_f2fs$(HOST_EXECUTABLE_SUFFIX)
 MKF2FSUSERIMG := $(HOST_OUT_EXECUTABLES)/mkf2fsuserimg.sh
 SIMG2IMG := $(HOST_OUT_EXECUTABLES)/simg2img$(HOST_EXECUTABLE_SUFFIX)