debian-bookworm-titan: add ccache

Add ccache, so it can be used when rebuilding the testsuite from source
from a development branch. Ccache is not used by default.

Related: osmo-dev I800062d0379295a6905851db29e820ff16217653
Change-Id: I94d22b8da9f897974c5913b2a8138c653c215446
---
M debian-bookworm-titan/Dockerfile
1 file changed, 18 insertions(+), 0 deletions(-)

diff --git a/debian-bookworm-titan/Dockerfile b/debian-bookworm-titan/Dockerfile
index 99a79c8..fcc00ba 100644
--- a/debian-bookworm-titan/Dockerfile
+++ b/debian-bookworm-titan/Dockerfile
@@ -19,6 +19,7 @@
 	apt-get install -y --no-install-recommends \
 		build-essential \
 		ca-certificates \
+		ccache \
 		git \
 		iputils-ping \
 		netcat-openbsd \
@@ -31,6 +32,10 @@
 		&& \
 	apt-get clean
 
+# Ccache is installed above so it can be optionally used when rebuilding the
+# testsuites inside the docker containers. Don't use it by default.
+ENV	USE_CCACHE=0
+
 # Binary-only transcoding library for RANAP/RUA/HNBAP to work around TITAN only implementing BER
 RUN	set -x && \
 	export DPKG_ARCH="$(dpkg --print-architecture)" && \

