[libgdata] build: Fix header inclusion checking for srcdir != builddir

[Philip Withnall <pwithnall src gnome org>]

commit d116a0b8721c3143d190b85f2781b4bde0a73a8b
Author: Philip Withnall <philip tecnocode co uk>
Date:   Sun Oct 17 15:13:35 2010 +0100

    build: Fix header inclusion checking for srcdir != builddir

 Makefile.am |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/Makefile.am b/Makefile.am
index 1e5240f..555c897 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -430,7 +430,7 @@ check-local: check-headers
 check-headers:
 	@any_missing=0; for header_file in $(public_headers); do \
 		if test "x$$header_file" != "x$(main_header)"; then \
-			if ! grep "#include <$$header_file>" $(main_header) >/dev/null; then \
+			if ! grep "#include <$$header_file>" $(top_srcdir)/$(main_header) >/dev/null; then \
 				echo "$(main_header) doesn't appear to include \"$$header_file\""; \
 				any_missing=1; \
 			fi; \