Factor out code building one file

Increase readability: decrease complexity of the build function and
preserve wandering off too much against 80-char "buoy"

setup/mk.sh

     exit 9
 }
 
+build1() {
+    local srcpath dstpath
+    srcpath=$1
+    dstpath=${srcpath%.in}
+    perl -pe "
+        s|__FFOO_INIT__|$ffoo_init|;
+        s|__FFOO_INI_PATH__|$FFOO_INI_PATH_GLOBAL:\\\$HOME/$FFOO_INI_PATH_USER|;
+        s|__VERSION__|$VERSION|;
+    " < $srcpath > $dstpath
+    echo $dstpath >> built.list
+}
+
 build() {
     ffoom init_path >& /dev/null \
         || die "-----" \
                "user and repeating the \`make install\` again." \
                "-----"
     local ffoo_init=$(ffoom init_path)
-    local srcpath dstpath
+    local srcpath
     find -type f -name '*.in' \
-        | while read srcpath;
-          do
-              dstpath=${srcpath%.in}
-              perl -pe "s|__FFOO_INIT__|$ffoo_init|;
-                        s|__FFOO_INI_PATH__|$FFOO_INI_PATH_GLOBAL:\\\$HOME/$FFOO_INI_PATH_USER|;
-                        s|__VERSION__|$VERSION|;" < $srcpath > $dstpath
-              echo $dstpath >> built.list
-          done
+     | while read srcpath;
+       do
+           build1 "$srcpath"
+       done
 }
 
 clean() {