docker: cleanup and split off ccache into separate function

docker_build_wrap.sh

@@ -7,26 +7,30 @@
 #   BUILD_DEPENDS  (may be used by config.sh, can be empty)
 set -e
 
+function activate_ccache {
+    # Link up the correct location for ccache
+    ln -s /parent-home/.ccache $HOME/.ccache
+
+    # Now install ccache
+    yum install -y ccache
+
+    # Create fake compilers and prepend them to the PATH
+    # Note that yum is supposed to create these for us,
+    # but I had trouble finding them
+    local ccache_dir=/usr/lib/ccache/compilers
+    mkdir -p $ccache_dir
+    ln -s /usr/bin/ccache $CCACHE_DIR/gcc
+    ln -s /usr/bin/ccache $CCACHE_DIR/g++
+    ln -s /usr/bin/ccache $CCACHE_DIR/cc
+    ln -s /usr/bin/ccache $CCACHE_DIR/c++
+    export PATH=$CCACHE_DIR:$PATH
+
+    # Prove to the developer that ccache is activated
+    which gcc
+}
+
 if [ $USE_CCACHE == 1 ]; then
-  # Link up the correct location for ccache
-  ln -s /parent-home/.ccache $HOME/.ccache
-
-  # Now install ccache
-  yum install -y ccache
-
-  # Create fake compilers and prepend them to the PATH
-  # Note that yum is supposed to create these for us,
-  # but I had trouble finding them
-  CCACHE_DIR=/usr/lib/ccache/compilers
-  mkdir -p $CCACHE_DIR
-  ln -s /usr/bin/ccache $CCACHE_DIR/gcc
-  ln -s /usr/bin/ccache $CCACHE_DIR/g++
-  ln -s /usr/bin/ccache $CCACHE_DIR/cc
-  ln -s /usr/bin/ccache $CCACHE_DIR/c++
-  export PATH=$CCACHE_DIR:$PATH
-  
-  # Prove to the developer that the correct gcc is used
-  which gcc
+    activate_ccache
 fi
 
 # Unicode width, default 32