build: Don't run glib-mkenums if there's nothing to do

This fixes the build without libsoup.

Closes: #296
Approved by: gatispaeglis

Makefile-libostree.am

@@ -33,9 +33,11 @@ lib_LTLIBRARIES += libostree-1.la
 libostreeincludedir = $(includedir)/ostree-1
 libostreeinclude_HEADERS = $(libostree_public_headers)
 
-ENUM_TYPES = \
-	$(srcdir)/src/libostree/ostree-fetcher.h \
-	$(NULL)
+ENUM_TYPES = $(NULL)
+
+if USE_LIBSOUP
+ENUM_TYPES += $(srcdir)/src/libostree/ostree-fetcher.h
+endif
 
 src/libostree/ostree-enumtypes.h: src/libostree/ostree-enumtypes.h.template $(ENUM_TYPES)
 	$(AM_V_GEN) $(GLIB_MKENUMS) \
@@ -48,12 +50,14 @@ src/libostree/ostree-enumtypes.c: src/libostree/ostree-enumtypes.c.template $(EN
 	--fhead "#include \"ostree-enumtypes.h\"" \
 	$(ENUM_TYPES) > $@.tmp && mv $@.tmp $@
 
+if USE_LIBSOUP
 ENUM_GENERATED = \
 	src/libostree/ostree-enumtypes.h \
 	src/libostree/ostree-enumtypes.c \
 	$(NULL)
 
 BUILT_SOURCES += $(ENUM_GENERATED)
+endif
 
 CLEANFILES += $(BUILT_SOURCES)
 

src/libostree/ostree-dummy-enumtypes.c

@@ -1,7 +1,7 @@
 /* This file declares a stub function that is only exported
  * to pacify ABI checkers - no one could really have used it.
  *
- * Copyright (C) 2015 Red Hat, Inc.
+ * Copyright (C) 2016 Red Hat, Inc.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public
@@ -23,7 +23,6 @@
 
 /* Exported for backwards compat - see 
  * https://bugzilla.gnome.org/show_bug.cgi?id=764131
- * https://github.com/ostreedev/ostree/pull/294
  */
 GType
 ostree_fetcher_config_flags_get_type (void)

src/libostree/ostree-dummy-enumtypes.h

@@ -1,7 +1,7 @@
 /* This file declares a stub function that is only exported
  * to pacify ABI checkers - no one could really have used it.
  *
- * Copyright (C) 2015 Red Hat, Inc.
+ * Copyright (C) 2016 Red Hat, Inc.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public