build: Fix scanner path in uninstalled pkg-config file

this was generating a pkg-config file that said wayland-scanner was
wayland/src/wayland-scanner when it's actually wayland/wayland-scanner

Signed-off-by: Derek Foreman <derekf@osg.samsung.com>
Acked-by: Bryce Harrington <bryce@osg.samsung.com>
Reviewed-by: Daniel Stone <daniels@collabora.com>
diff --git a/src/wayland-scanner-uninstalled.pc.in b/src/wayland-scanner-uninstalled.pc.in
index 8dcfef3..132f42d 100644
--- a/src/wayland-scanner-uninstalled.pc.in
+++ b/src/wayland-scanner-uninstalled.pc.in
@@ -1,5 +1,5 @@
 pkgdatadir=@abs_top_srcdir@
-wayland_scanner=@abs_builddir@/wayland-scanner
+wayland_scanner=@abs_top_builddir@/wayland-scanner
  
 Name: Wayland Scanner
 Description: Wayland scanner (not installed)