Don’t use GNOME_COMPILE_WARNINGS

GNOME_COMPILE_WARNINGS is still being used, despite its deprecated
status. This commit also tweaks configure.ac a little, removing
redundant macro calls and definitions and quoting all macro arguments.

https://bugzilla.gnome.org/show_bug.cgi?id=770466

src/Makefile.am

@@ -3,12 +3,14 @@ AM_CPPFLAGS =                                             \
     -DPACKAGE_SRC_DIR=\""$(srcdir)"\"                     \
     -DPACKAGE_DATA_DIR=\""$(pkgdatadir)"\"                \
     -DUI_DATA_DIR=\""$(pkgdatadir)/style"\"               \
-    $(MAINTAINER_COMPILER_FLAGS)                          \
     $(WARN_CFLAGS)                                        \
     -DEDS_DISABLE_DEPRECATED                              \
     -DGOA_API_IS_SUBJECT_TO_CHANGE                        \
     $(CALENDAR_CFLAGS)
 
+AM_LDFLAGS = \
+	$(WARN_LDFLAGS)
+
 bin_PROGRAMS = gnome-calendar
 
 BUILT_SOURCES =                                           \