Merge pull request #2200 from stewart-ibm/hb-ccache

hostboot: enable use of ccache
diff --git a/openpower/package/hostboot/hostboot.mk b/openpower/package/hostboot/hostboot.mk
index 1bfe016..d83f073 100644
--- a/openpower/package/hostboot/hostboot.mk
+++ b/openpower/package/hostboot/hostboot.mk
@@ -16,7 +16,7 @@
 
 HOSTBOOT_ENV_VARS=$(TARGET_MAKE_ENV) PERL_USE_UNSAFE_INC=1 \
     CONFIG_FILE=$(BR2_EXTERNAL_OP_BUILD_PATH)/configs/hostboot/$(BR2_HOSTBOOT_CONFIG_FILE) \
-    OPENPOWER_BUILD=1 CROSS_PREFIX=$(TARGET_CROSS) HOST_PREFIX="" HOST_BINUTILS_DIR=$(HOST_BINUTILS_DIR) \
+    OPENPOWER_BUILD=1 CROSS_PREFIX="$(CCACHE) $(TARGET_CROSS)" HOST_PREFIX="" HOST_BINUTILS_DIR=$(HOST_BINUTILS_DIR) \
     HOSTBOOT_VERSION=`cat $(HOSTBOOT_VERSION_FILE)`
 
 define HOSTBOOT_BUILD_CMDS