[glom] Build: reference docs: Build when srcdir != builddir

[Murray Cumming <murrayc src gnome org>]

commit abd42e290cd8ed9ee8e88bf2f5e2ed957e54d0e5
Author: Murray Cumming <murrayc murrayc com>
Date:   Fri Sep 27 16:23:01 2019 +0200

    Build: reference docs: Build when srcdir != builddir

 docs/libglom_reference/Makefile.am | 3 ++-
 glom/libglom/filelist.am           | 9 ++++++++-
 2 files changed, 10 insertions(+), 2 deletions(-)
---
diff --git a/docs/libglom_reference/Makefile.am b/docs/libglom_reference/Makefile.am
index bd2599ea..6ccb38a5 100644
--- a/docs/libglom_reference/Makefile.am
+++ b/docs/libglom_reference/Makefile.am
@@ -18,7 +18,8 @@
 include $(top_srcdir)/glom/libglom/filelist.am
 
 book_name  = libglom-$(GLOM_ABI_VERSION)
-doc_input  = $(addprefix $(top_srcdir)/,$(libglom_headers))
+doc_input  = $(addprefix $(top_srcdir)/,$(libglom_headers)) \
+            $(addprefix $(top_builddir)/,$(libglom_headers_generated))
 doc_outdir = .
 
 include $(top_srcdir)/doc-reference.am
diff --git a/glom/libglom/filelist.am b/glom/libglom/filelist.am
index 6243b494..19d1c96a 100644
--- a/glom/libglom/filelist.am
+++ b/glom/libglom/filelist.am
@@ -21,7 +21,6 @@ libglom_toplevel_headers =                            \
        glom/libglom/appstate.h                         \
        glom/libglom/algorithms_utils.h \
        glom/libglom/init.h                             \
-       glom/libglom/libglom_config.h                   \
        glom/libglom/sharedptr.h                        \
        glom/libglom/standard_table_prefs_fields.h      \
        glom/libglom/utils.h                            \
@@ -32,6 +31,10 @@ libglom_toplevel_headers =                           \
        glom/libglom/report_builder.h \
        glom/libglom/translations_po.h
 
+# These will be in the build directory, not the source directory.
+libglom_toplevel_headers_generated  = \
+       glom/libglom/libglom_config.h
+
 libglom_data_structure_headers =                               \
        glom/libglom/data_structure/database_title.h            \
        glom/libglom/data_structure/choicevalue.h               \
@@ -98,6 +101,10 @@ libglom_headers =                           \
        $(libglom_d_bakery_headers)             \
        $(libglom_d_b_view_headers)
 
+# These will be in the build directory, not the source directory.
+libglom_headers_generated = \
+       $(libglom_toplevel_headers_generated)
+
 # Private source and header files:
 
 libglom_sources =                                                      \