libcgroup: Added new package.

libcgroup also contains cgroup-utils, which make it very handy to work
with user defined cgroups settings.
It let's you define cgroups in a json like config file and execute them on the cmdline.

Example:

/etc/cgroup.conf:
----------------
group lowbob {
        cpu { cpu.shares="1"; }
        cpuacct { cpuset.cpu = "0" }
        memory { memory.limit_in_bytes = 10m; }
        blkio { ... }
	...
}
----------------
cgconfigparser -l /etc/cgroup.conf
cgexec -g cpu,memory,blkio:/lowbob cpuintense-task

Signed-off-by: Daniel Danzberger <daniel@dd-wrt.com>

libs/libcgroup/Makefile

@@ -0,0 +1,60 @@
+include $(TOPDIR)/rules.mk
+
+PKG_NAME:=libcgroup
+PKG_VERSION:=0.41
+PKG_RELEASE:=1
+PKG_LICENSE:=LGPL
+PKG_LICENSE_FILES:=COPYING
+
+PKG_SOURCE:=$(PKG_NAME)-$(PKG_VERSION).tar.bz2
+PKG_SOURCE_URL:=@SF/libcg
+PKG_HASH:=e4e38bdc7ef70645ce33740ddcca051248d56b53283c0dc6d404e17706f6fb51
+PKG_MAINTAINER:=Daniel Danzberger <daniel@dd-wrt.com>
+
+PKG_BUILD_PARALLEL:=1
+PKG_FIXUP:=autoreconf
+
+include $(INCLUDE_DIR)/package.mk
+
+define Package/libcgroup
+  TITLE:=CGroup config and exec library
+  SECTION:=libs
+  CATEGORY:=Libraries
+  DEPENDS:=+musl-fts +@KERNEL_CGROUPS
+endef
+
+define Package/cgroup-tools
+  TITLE:=CGroup config and exec tools
+  DEPENDS:=+libcgroup
+  CATEGORY:=Utilities
+endef
+
+define Package/libcgroup/description
+  Helpers utils for working with cgroups.
+endef
+
+CONFIGURE_ARGS += --enable-tools \
+		--enable-shared \
+		--disable-daemon \
+		--disable-pam
+
+define Build/InstallDev
+	$(INSTALL_DIR) $(1)/usr/include $(1)/usr/lib $(1)/usr/lib/pkgconfig
+	$(CP) $(PKG_BUILD_DIR)/include/libcgroup.h $(1)/usr/include
+	$(CP) $(PKG_BUILD_DIR)/include/libcgroup $(1)/usr/include
+	$(CP) $(PKG_BUILD_DIR)/src/.libs/libcgroup.so* $(1)/usr/lib
+	$(CP) $(PKG_BUILD_DIR)/libcgroup.pc $(1)/usr/lib/pkgconfig/
+endef
+
+define Package/libcgroup/install
+	$(INSTALL_DIR) $(1)/usr/lib
+	$(CP) $(PKG_BUILD_DIR)/src/.libs/libcgroup.so* $(1)/usr/lib
+endef
+
+define Package/cgroup-tools/install
+	$(INSTALL_DIR) $(1)/usr/bin
+	$(INSTALL_BIN) $(PKG_BUILD_DIR)/src/tools/.libs/* $(1)/usr/bin
+endef
+
+$(eval $(call BuildPackage,libcgroup))
+$(eval $(call BuildPackage,cgroup-tools))

libs/libcgroup/patches/0001-musl-fts-configure.patch

@@ -0,0 +1,24 @@
+diff --git a/configure.in b/configure.in
+index 75f4a51..f70b37c 100644
+--- a/configure.in
++++ b/configure.in
+@@ -193,6 +193,19 @@ if test x$with_pam = xtrue; then
+ 		header files!])])
+ fi
+ 
++AC_CHECK_LIB(
++	[fts],
++	[fts_open],
++	[],
++	[AC_MSG_ERROR([Cannot compile without fts!])]
++)
++
++AC_CHECK_HEADERS(
++	[fts.h],
++	[],
++	[AC_MSG_ERROR([Cannot compile without fts.h])]
++)
++
+ AC_CONFIG_FILES([Makefile
+ 	tests/Makefile
+ 	tests/tools/testenv.sh