always use ccache from OpenADK, problem reported by Diez

scripts/prereq.sh

@@ -596,11 +596,6 @@ if ! which mkisofs >/dev/null 2>&1; then
   host_build_cdrtools=1
 fi
 
-host_build_ccache=0
-if ! which ccache >/dev/null 2>&1; then
-  host_build_ccache=1
-fi
-
 host_build_genext2fs=0
 if ! which genext2fs >/dev/null 2>&1; then
   host_build_genext2fs=1
@@ -686,9 +681,6 @@ if [ $host_build_xz -eq 1 ]; then
   printf "\t%s\n" "select ADK_HOST_BUILD_XZ" >> $topdir/target/config/Config.in.prereq
 fi
 # optional
-if [ $host_build_ccache -eq 1 ]; then
-  printf "\t%s\n" "select ADK_HOST_BUILD_CCACHE if ADK_HOST_NEED_CCACHE" >> $topdir/target/config/Config.in.prereq
-fi
 if [ $host_build_cdrtools -eq 1 ]; then
   printf "\t%s\n" "select ADK_HOST_BUILD_CDRTOOLS if ADK_HOST_NEED_CDRTOOLS" >> $topdir/target/config/Config.in.prereq
 fi

target/config/Config.in.adk

@@ -75,7 +75,7 @@ config ADK_DISABLE_TARGET_KERNEL_PATCHES
 
 config ADK_USE_CCACHE
 	bool "Use ccache to speedup recompilation"
-	select ADK_HOST_NEED_CCACHE
+	select ADK_HOST_BUILD_CCACHE
 	default n
 	help
 	  Useful if you have enough space for the cache and need speedup compilation.

target/config/Config.in.tools

@@ -142,10 +142,6 @@ config ADK_HOST_BUILD_GENIMAGE
 	select ADK_HOST_BUILD_DOSFSTOOLS
 	default n
 
-config ADK_HOST_NEED_CCACHE
-	bool
-	default n
-
 config ADK_HOST_BUILD_CCACHE
 	bool
 	default n