fix includedir in pkg-config file, forgot the patch

package/libffi/patches/patch-libffi_pc_in

@@ -0,0 +1,11 @@
+--- libffi-3.0.9.orig/libffi.pc.in	2009-12-31 13:38:48.000000000 +0100
++++ libffi-3.0.9/libffi.pc.in	2010-12-11 01:46:04.000000000 +0100
+@@ -1,7 +1,7 @@
+ prefix=@prefix@
+ exec_prefix=@exec_prefix@
+ libdir=@libdir@
+-includedir=${libdir}/@PACKAGE_NAME@-@PACKAGE_VERSION@/include
++includedir=@includedir@
+ 
+ Name: @PACKAGE_NAME@
+ Description: Library supporting Foreign Function Interfaces