aufs-utils-native: define CC

With the new host tools path filtering, aufs-utils-native fails to build
as follows:

| ERROR: oe_runmake failed
| cc
| -isystem/build/tmp/work/x86_64-linux/aufs-util-native/3.14+gitAUTOINC+b59a2167a1-r0/recipe-sysroot-native/usr/include
| -O2 -pipe -O -Wall
| -I/build/tmp/work/x86_64-linux/aufs-util-native/3.14+gitAUTOINC
+b59a2167a1-r0/git/include
| -I/build/tmp/work/x86_64-linux/aufs-util-native/3.14+gitAUTOINC+b59a2167a1-r0/git/libau
| -D_GNU_SOURCE -I./libau -DAUFHSM_CMD=\"/usr/bin/aufhsm\"
| -DMOUNT_CMD=\"/bin/mount\" -DUMOUNT_CMD=\"/bin/um
ount\"
| -L/build/tmp/work/x86_64-linux/aufs-util-native/3.14+gitAUTOINC+b59a2167a1-r0/recipe-sysroot-native/usr/lib
| -L/build/tmp/work/x86_64-linux/aufs-util-native/3.14+gitAUTOINC+b59a2167a1-r0/recipe-sysro
ot-native/lib
| -Wl,-rpath-link,/build/tmp/work/x86_64-linux/aufs-util-native/3.14+gitAUTOINC+b59a2167a1-r0/recipe-sysroot-native/usr/lib
| -Wl,-rpath-link,/build/tmp/work/x86_64-linux/aufs-util-native/3.14+gi
tAUTOINC+b59a2167a1-r0/recipe-sysroot-native/lib
| -Wl,-rpath,/build/tmp/work/x86_64-linux/aufs-util-native/3.14+gitAUTOINC+b59a2167a1-r0/recipe-sysroot-native/usr/lib
| -Wl,-rpath,/build/tmp/work/x86_64-linux
/aufs-util-native/3.14+gitAUTOINC+b59a2167a1-r0/recipe-sysroot-native/lib
| -Wl,-O1  c2sh.c   -o c2sh
| make: cc: Command not found
| <builtin>: recipe for target 'c2sh' failed

While we could get 'cc' added to the tools whitelist, it is just as easy
to redefine CC to be gcc, which is already passed through.

Signed-off-by: Bruce Ashfield <bruce.ashfield@windriver.com>
Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>

meta-filesystems/recipes-utils/aufs-util/aufs-util_git.bb

@@ -41,7 +41,7 @@ do_compile () {
 }
 
 do_compile_class-native () {
-    oe_runmake tools CPPFLAGS="-I${S}/include -I${S}/libau"
+    oe_runmake tools CPPFLAGS="-I${S}/include -I${S}/libau" CC="${BUILD_CC}"
 }
 
 do_install () {