build: ipkg-build use fakeroot with PKG_FILE_MODES

The `ipkg-build` script converts a folder into a `opkg` installable
package. Until now it would use root:root for all packages and try to
preserve file modes.

This has the two drawbacks of packages want to add non-root files or add
SUID files, like the `sudo` package does.

To give more flexibility regarding file modes and avoid init script
hacks, a new variable called `PKG_FILE_MODES`. The variable contains a
list of files modes in the format `path:owner:group:mode`.

An example for the `sudo` package below:

```
PKG_FILE_MODES:=\
        /usr/bin/sudo:root:root:4755 \
        /etc/sudoers:root:root:0440
```

The `ipkg-build` now runs within a fakeroot environment to set any mode
and directly store it in the resulting `ipk` package archive.

Both options `-o` and `-g` are no longer required due to the introduction
of the more flexible `-m` options, which takes the `PKG_FILE_MODES` as
input.

Lastly the option `-c` is removed as it's unused within the script.

Signed-off-by: Paul Spooren <mail@aparcar.org>

include/package-ipkg.mk

@@ -9,10 +9,6 @@ ifndef DUMP
   include $(INCLUDE_DIR)/feeds.mk
 endif
 
-# invoke ipkg-build with some default options
-IPKG_BUILD:= \
-  $(SCRIPT_DIR)/ipkg-build -c -o 0 -g 0
-
 IPKG_REMOVE:= \
   $(SCRIPT_DIR)/ipkg-remove
 
@@ -262,7 +258,7 @@ $(_endef)
     endif
 
 	$(INSTALL_DIR) $$(PDIR_$(1))
-	$(IPKG_BUILD) $$(IDIR_$(1)) $$(PDIR_$(1))
+	$(FAKEROOT) $(SCRIPT_DIR)/ipkg-build -m "$(PKG_FILE_MODES)" $$(IDIR_$(1)) $$(PDIR_$(1))
 	@[ -f $$(IPKG_$(1)) ]
 
     $(1)-clean: