ccache: Speed up building.

- Disable compression for ccache's cached files.
- Disable the hashing of the CWD inside debug information. This
  increases the cache hits drastically.

Signed-off-by: Markus Gothe <[email protected]>

rules.mk

@@ -342,6 +342,8 @@ ifneq ($(CONFIG_CCACHE),)
   TARGET_CXX:= ccache $(TARGET_CXX)
   HOSTCC:= ccache $(HOSTCC)
   HOSTCXX:= ccache $(HOSTCXX)
+  export CCACHE_NOHASHDIR:=true
+  export CCACHE_NOCOMPRESS:=true
   export CCACHE_BASEDIR:=$(TOPDIR)
   export CCACHE_DIR:=$(if $(call qstrip,$(CONFIG_CCACHE_DIR)),$(call qstrip,$(CONFIG_CCACHE_DIR)),$(TOPDIR)/.ccache)
   export CCACHE_COMPILERCHECK:=%compiler% -dumpmachine; %compiler% -dumpversion