epm print: add filesize verb, add get_filesize function

bin/epm-print

@@ -513,6 +513,9 @@ epm_print()
         "constructname")
             construct_name "$@"
             ;;
+        "filesize")
+            get_filesize "$@"
+            ;;
         "info")
             export EPMVERSION
             $DISTRVENDOR "$@"

bin/epm-sh-functions

@@ -724,6 +724,16 @@ regexp_subst()
     sed -i -r -e "$expression" "$@"
 }
 
+get_filesize()
+{
+    if stat -f%z "$1" >/dev/null 2>&1; then
+        stat -f%z "$1"
+    else
+        # coreutils
+        stat -c%s "$1"
+    fi
+}
+
 # TODO: why we can't use epm directly?
 try_assure_exists()
 {