Add builtin ccache support, enabled by default

Add builtin support for using ccache in pbuilder and enable it by
default.  Ship a new /var/cache/pbuilder/ccache dir and bind-mount and
chown it to BUILDUSERID at build time.  Install/remove ccache
automatically on create/update if CCACHEDIR is set/unset.  Update docs
and remove old ccache config example.  Add a NEWS entry featuring the
change.

1 files changed, 2 insertions, 0 deletions

diff --git a/pbuilderrc b/pbuilderrc
index ec06a95..96c4214 100755
--- a/pbuilderrc
+++ b/pbuilderrc
@@ -28,6 +28,8 @@ APTCACHEHARDLINK="yes"
 REMOVEPACKAGES=""
 #HOOKDIR="/usr/lib/pbuilder/hooks"
 HOOKDIR=""
+# NB: this var is private to pbuilder; ccache uses "CCACHE_DIR" instead
+CCACHEDIR="/var/cache/pbuilder/ccache"
 
 # make debconf not interact with user
 export DEBIAN_FRONTEND="noninteractive"