sdk: explicitely remove ccache directories when packing SDK

Upon first invocation, the ccache program will create the required directory
hierarchy so there is no point in shipping these empty directories.

Removing those paths also avoids shipping dangling symlinks in case the
directories got linked elsewhere, e.g. into a shared global cache.

Signed-off-by: Jo-Philipp Wich <jo@mein.io>

target/sdk/Makefile

@@ -17,6 +17,7 @@ SDK_NAME:=$(VERSION_DIST_SANITIZED)-sdk-$(if $(CONFIG_VERSION_FILENAMES),$(VERSI
 SDK_BUILD_DIR:=$(BUILD_DIR)/$(SDK_NAME)
 
 STAGING_SUBDIR_HOST := staging_dir/host
+STAGING_SUBDIR_TARGET := staging_dir/$(TARGET_DIR_NAME)
 STAGING_SUBDIR_TOOLCHAIN := staging_dir/toolchain-$(ARCH)$(ARCH_SUFFIX)_gcc-$(GCCV)_$(LIBC)-$(LIBCV)$(if $(CONFIG_arm),_eabi)
 
 EXCLUDE_DIRS:=*/ccache/* \
@@ -118,6 +119,11 @@ $(BIN_DIR)/$(SDK_NAME).tar.xz: clean
 		$(TOPDIR)/package/kernel/linux \
 		$(SDK_BUILD_DIR)/package/
 
+	-rm -rf \
+		$(SDK_BUILD_DIR)/$(STAGING_SUBDIR_HOST)/ccache \
+		$(SDK_BUILD_DIR)/$(STAGING_SUBDIR_TARGET)/ccache \
+		$(SDK_BUILD_DIR)/$(STAGING_SUBDIR_TOOLCHAIN)/ccache
+
 	-rm -f $(SDK_BUILD_DIR)/feeds.conf.default
 	$(if $(BASE_FEED),echo "$(BASE_FEED)" > $(SDK_BUILD_DIR)/feeds.conf.default)
 	if [ -f $(TOPDIR)/feeds.conf ]; then \