[librsvg/librsvg-2.44] build: Fix building with srcdir != builddir

[Federico Mena Quintero <federico src gnome org>]

commit f275732d6a55d0e103f400ff108e1addbc8625d3
Author: Mathieu Bridon <bochecha daitauha fr>
Date:   Mon Sep 10 14:01:22 2018 +0200

    build: Fix building with srcdir != builddir
    
    This came up in the Freedesktop-Sdk project:
    
        https://gitlab.com/freedesktop-sdk/freedesktop-sdk/merge_requests/507#note_99932762

 Makefile.am | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/Makefile.am b/Makefile.am
index 3792d40b..6bf1e581 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -374,7 +374,7 @@ VAPIGEN_VAPIS = librsvg-$(RSVG_API_VERSION).vapi
 
 librsvg_@RSVG_API_VERSION_U@_vapi_DEPS = gio-2.0 cairo
 librsvg_@RSVG_API_VERSION_U@_vapi_METADATADIRS = $(srcdir)
-librsvg_@RSVG_API_VERSION_U@_vapi_FILES = Rsvg-$(RSVG_API_VERSION).gir Rsvg-$(RSVG_API_VERSION)-custom.vala
+librsvg_@RSVG_API_VERSION_U@_vapi_FILES = Rsvg-$(RSVG_API_VERSION).gir 
$(srcdir)/Rsvg-$(RSVG_API_VERSION)-custom.vala
 
 vapidir = $(datadir)/vala/vapi
 vapi_DATA = $(VAPIGEN_VAPIS)