fix includedir in pkg-config file

package/libffi/Makefile

@@ -5,11 +5,11 @@ include ${TOPDIR}/rules.mk
 
 PKG_NAME:=		libffi
 PKG_VERSION:=		3.0.9
-PKG_RELEASE:=		1
+PKG_RELEASE:=		2
 PKG_MD5SUM:=		1f300a7a7f975d4046f51c3022fa5ff1
 PKG_DESCR:=		Foreign Function Interface library
 PKG_SECTION:=		libs
-PKG_URL:=		http://sourceware.org/libffi
+PKG_URL:=		http://sourceware.org/libffi/
 PKG_SITES:=		ftp://sourceware.org/pub/libffi/
 
 include ${TOPDIR}/mk/package.mk