[glom] configure.ac: Use -Wshadow with --enable-warnings=fatal.

[Murray Cumming <murrayc src gnome org>]

commit bf982f53bec0f26b59b12ae852bc587b34790197
Author: Murray Cumming <murrayc murrayc com>
Date:   Mon Jul 6 13:50:05 2015 +0200

    configure.ac: Use -Wshadow with --enable-warnings=fatal.

 configure.ac |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/configure.ac b/configure.ac
index 2052748..a0102bc 100644
--- a/configure.ac
+++ b/configure.ac
@@ -223,7 +223,7 @@ MM_ARG_ENABLE_WARNINGS([GLOM_WFLAGS],
 AC_LANG([C++])
 MM_ARG_ENABLE_WARNINGS([GLOM_WXXFLAGS],
                        [-Wall],
-                       [-pedantic -Wall -Wextra -Wsuggest-override -Wformat-security -Wno-long-long 
-Wno-missing-field-initializers -DGSEAL_ENABLE],
+                       [-pedantic -Wall -Wextra -Wsuggest-override -Wshadow -Wformat-security -Wno-long-long 
-Wno-missing-field-initializers -DGSEAL_ENABLE],
                        [G GDK GDK_PIXBUF GTK GDA GLIBMM GDKMM CAIROMM PANGOMM GTKMM SIGCXX LIBGDAMM])
 
 AC_CHECK_FUNCS([strptime])