[shotwell] build: Disable misleading warnings caused by valac

[Jens Georg <jensgeorg src gnome org>]

commit 2dd03b3ea8a50fc031c91f79df65b9d2a4d25b13
Author: Jens Georg <mail jensge org>
Date:   Fri Oct 21 17:39:09 2016 +0200

    build: Disable misleading warnings caused by valac
    
    Signed-off-by: Jens Georg <mail jensge org>

 common.am |    4 +++-
 1 files changed, 3 insertions(+), 1 deletions(-)
---
diff --git a/common.am b/common.am
index 20a66c6..da05cba 100644
--- a/common.am
+++ b/common.am
@@ -12,7 +12,9 @@ COMMON_CFLAGS = \
        -DGETTEXT_PACKAGE='"$(GETTEXT_PACKAGE)"' \
        -D_LANG_SUPPORT_DIR='"$(prefix)/share/locale"' \
        -D_LIBEXECDIR='"$(libexecdir)"' \
-       -D_LIB='"$(libdir)"'
+       -D_LIB='"$(libdir)"' \
+       -Wno-incompatible-pointer-types \
+       -Wno-discarded-qualifiers
 
 if IS_GITVERSION
 COMMON_CFLAGS += -D_GIT_VERSION='"@GITVER@"'