If ccache is installed, cache compilations

gitlab/before_build.sh

@@ -15,7 +15,17 @@ if [ ! -d ${PREFIX} ]; then
   log_info "Creating virtualenv installation at ${PREFIX}..."
   run_cmd ${BOB_PREFIX_PATH}/bin/virtualenv --system-site-packages ${PREFIX}
 else
-  log_warn "Prefix directory ${PREFIX} exists, not re-installing..."
+  log_info "Prefix directory ${PREFIX} exists, not re-installing..."
+fi
+
+# Configures CCACHE
+use_ccache=`which ccache`
+if [ -z "${use_ccache}" ]; then
+  log_warn "Cannot find ccache, compiling from scratch..."
+else
+  log_info "ccache installed at ${use_ccache}, caching compilations..."
+  run_cmd ln -s ${use_cacche} ${PREFIX}/bin/gcc
+  run_cmd ln -s ${use_cacche} ${PREFIX}/bin/g++
 fi
 
 # Source the newly created virtualenv