Make the ccache size configurable

Dockerfile

@@ -23,6 +23,11 @@ ENV USER root
 # WARNING: disabling this may slow down a lot your builds!
 ENV USE_CCACHE 1
 
+# ccache maximum size. It should be a number followed by an optional suffix: k,
+# M, G, T (decimal), Ki, Mi, Gi or Ti (binary). The default suffix is G. Use 0
+# for no limit.
+ENV CCACHE_SIZE 50G
+
 # Environment for the LineageOS Branch name
 # See https://github.com/LineageOS/android_vendor_cm/branches for possible options
 ENV BRANCH_NAME 'cm-14.1'

src/init.sh

@@ -25,7 +25,7 @@ find /root/userscripts ! -type d -perm /g=w,o=w -exec echo ">> [$(date)] {} is w
 
 # Initialize CCache if it will be used
 if [ "$USE_CCACHE" = 1 ]; then
-  ccache -M 100G 2>&1
+  ccache -M $CCACHE_SIZE 2>&1
 fi
 
 # Initialize Git user information