[shotwell/wip/autotools] build: Fix makefile generation

[Jens Georg <jensgeorg src gnome org>]

commit 092a951acc6398f0b527b7c1cd97ce831f9751fc
Author: Jens Georg <mail jensge org>
Date:   Thu Jun 30 22:23:37 2016 +0200

    build: Fix makefile generation
    
    Signed-off-by: Jens Georg <mail jensge org>

 common.am    |    2 +-
 configure.ac |    5 ++++-
 2 files changed, 5 insertions(+), 2 deletions(-)
---
diff --git a/common.am b/common.am
index 339934a..6129cf1 100644
--- a/common.am
+++ b/common.am
@@ -1,7 +1,7 @@
 # --enable-checking needs to come first to not trigger
 #  https://debbugs.gnu.org/cgi/bugreport.cgi?bug=18734
 COMMON_VALAFLAGS = \
-       --enable-checking -g --target-glib=2.32 --thread --fatal-warnings \
+       --enable-checking --target-glib=2.32 --thread --fatal-warnings \
        --enable-experimental --enable-deprecated
 
 COMMON_CFLAGS = \
diff --git a/configure.ac b/configure.ac
index 8c49ea6..79ca9aa 100644
--- a/configure.ac
+++ b/configure.ac
@@ -78,7 +78,10 @@ PKG_PROG_PKG_CONFIG([0.22])
 AX_REQUIRE_DEFINED([GLIB_GSETTINGS])
 GLIB_GSETTINGS
 
-
+# Using -g in target's _VALAFLAGS triggers a bug in Vala's automake integration
+# that causes invalid makefile generation, so we put it into global VALAFLAGS
+VALAFLAGS="-g"
+AC_SUBST([VALAFLAGS])
 
 dnl ***********************************************************************
 dnl Check for required packages