Enable subdir-objects to avoid automake warnings

Avoid warning:
src/bin/Makefile.am:18: warning: source file '$(builddir)/game_world.c'
  is in a subdirectory,
src/bin/Makefile.am:18: but option 'subdir-objects' is disabled
[...]
automake: You are advised to start using 'subdir-objects' option throughout your
automake: project, to avoid future incompatibilities.

2 files changed, 3 insertions, 3 deletions

diff --git a/configure.ac b/configure.ac
index ee55dbf..5a2008d 100644
--- a/configure.ac
+++ b/configure.ac
@@ -27,7 +27,7 @@ AC_CANONICAL_BUILD
 AC_CANONICAL_HOST
 AC_ISC_POSIX
 
-AM_INIT_AUTOMAKE(1.6 dist-bzip2)
+AM_INIT_AUTOMAKE(1.6 dist-bzip2 subdir-objects)
 AC_CONFIG_HEADERS(config.h)
 m4_ifdef([AM_SILENT_RULES], [AM_SILENT_RULES([yes])])
 
diff --git a/src/bin/Makefile.am b/src/bin/Makefile.am
index 032f699..1e22409 100644
--- a/src/bin/Makefile.am
+++ b/src/bin/Makefile.am
@@ -16,13 +16,13 @@ bin_PROGRAMS += efbb_ql
 endif
 
 GAME_SOURCES = \
-        $(builddir)/game_world.c \
+        game_world.c \
         main.c \
         main_screen.c \
         level_select_screen.c \
         cannon.c \
         sound.c \
-        score.c \
+        score.c \
         bg.c
 
 efbb_LDADD = @EFBB_LIBS@