[shotwell] build: Call pkg-config only once

[Jens Georg <jensgeorg src gnome org>]

commit 423a70b1752c1fd4c8bccf492dc77faaf1f9647a
Author: Jens Georg <mail jensge org>
Date:   Tue Apr 19 21:32:28 2016 +0200

    build: Call pkg-config only once
    
    Signed-off-by: Jens Georg <mail jensge org>

 Makefile                   |    4 ++--
 plugins/Makefile.plugin.mk |    5 +++--
 2 files changed, 5 insertions(+), 4 deletions(-)
---
diff --git a/Makefile b/Makefile
index 914618a..900cce4 100644
--- a/Makefile
+++ b/Makefile
@@ -388,11 +388,11 @@ PACKAGE_ORIG_XZ = $(PROGRAM)_`parsechangelog | grep Version | sed 's/.*: //'`.or
 
 VALAFLAGS := $(VALAFLAGS) $(VALA_DEFINES) --vapidir=plugins/
 
-VALA_CFLAGS := `pkg-config --cflags $(EXT_PKGS) $(DIRECT_LIBS) gthread-2.0` \
+VALA_CFLAGS := $(shell pkg-config --cflags $(EXT_PKGS) $(DIRECT_LIBS)) \
        $(foreach hdir,$(HEADER_DIRS),-I$(hdir)) \
        $(foreach def,$(DEFINES),-D$(def))
 
-VALA_LDFLAGS := `pkg-config --libs $(EXT_PKGS) $(DIRECT_LIBS) gthread-2.0`
+VALA_LDFLAGS := $(shell pkg-config --libs $(EXT_PKGS) $(DIRECT_LIBS) gthread-2.0)
 
 # REQUIRED_CFLAGS absolutely get appended to CFLAGS, whatever the
 # the value of CFLAGS in the environment
diff --git a/plugins/Makefile.plugin.mk b/plugins/Makefile.plugin.mk
index 723e708..317aac5 100644
--- a/plugins/Makefile.plugin.mk
+++ b/plugins/Makefile.plugin.mk
@@ -34,8 +34,9 @@ SRC_FILES := ../common/Resources.vala $(SRC_FILES)
 CFILES := $(notdir $(SRC_FILES:.vala=.c))
 OFILES := $(notdir $(SRC_FILES:.vala=.o))
 
-CFLAGS := `pkg-config --print-errors --cflags $(EXT_PKGS) $(PLUGIN_PKGS)` -nostdlib -export-dynamic 
$(PLUGIN_CFLAGS)
-LIBS := `pkg-config --print-errors --libs $(EXT_PKGS) $(PLUGIN_PKGS)`
+CFLAGS := $(shell pkg-config --print-errors --cflags $(EXT_PKGS) $(PLUGIN_PKGS)) \
+       -nostdlib -export-dynamic $(PLUGIN_CFLAGS)
+LIBS := $(shell pkg-config --print-errors --libs $(EXT_PKGS) $(PLUGIN_PKGS))
 DEFINES := -D_VERSION='"$(PLUGINS_VERSION)"' -DGETTEXT_PACKAGE='"shotwell"'
 
 all: $(PLUGIN).so