icecc: Enable icecc also for install step

Some packages are calling the compiler in the install step. In this
case either the build breaks or icecc is not used for building. The
proper environment has to be set to enable icecc based building.

(From OE-Core rev: bb1366cebb60593fc21fd7a9a678a159da8ec81c)

Signed-off-by: Tobias Henkel <tobias.henkel@bmw-carit.de>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/classes/icecc.bbclass

@@ -258,6 +258,6 @@ do_compile_kernelmodules_prepend() {
     set_icecc_env
 }
 
-#do_install_prepend() {
-#    set_icecc_env
-#}
+do_install_prepend() {
+    set_icecc_env
+}