Allow master projects to disable features.

When built as a subproject, we need the master to decide what features
to activate or not. This could lead to reduced dependences.

This patch also allows to build without imlib2.

build/autotools/m4/lol-conf.m4

@@ -135,11 +135,13 @@ AM_CONDITIONAL(LOL_USE_LIBPNG, test "${ac_cv_my_have_libpng}" != "no")
 
 dnl  Use Imlib2?
 ac_cv_my_have_imlib2="no"
-PKG_CHECK_MODULES(IMLIB2, imlib2, [ac_cv_my_have_imlib2="yes"], [:])
-if test "${ac_cv_my_have_imlib2}" != "no"; then
-  AC_DEFINE(LOL_USE_IMLIB2, 1, Define to 1 to use Imlib2)
-  LOL_CFLAGS="${LOL_CFLAGS} ${IMLIB2_CFLAGS}"
-  LOL_LIBS="${LOL_LIBS} ${IMLIB2_LIBS}"
+if test "${enable_imlib2}" != "no"; then
+  PKG_CHECK_MODULES(IMLIB2, imlib2, [ac_cv_my_have_imlib2="yes"], [:])
+  if test "${ac_cv_my_have_imlib2}" != "no"; then
+    AC_DEFINE(LOL_USE_IMLIB2, 1, Define to 1 to use Imlib2)
+    LOL_CFLAGS="${LOL_CFLAGS} ${IMLIB2_CFLAGS}"
+    LOL_LIBS="${LOL_LIBS} ${IMLIB2_LIBS}"
+  fi
 fi
 AM_CONDITIONAL(LOL_USE_IMLIB2, test "${ac_cv_my_have_imlib2}" = "yes")
 

build/autotools/m4/lol-subproject.m4

@@ -20,7 +20,7 @@ dnl  Build and configure Lol Engine before our repository
 dnl  Ensure $lol_srcdir and $lol_builddir are properly set
 dnl
 
-ac_configure_args="${ac_configure_args} --enable-subproject"
+ac_configure_args="${ac_configure_args} --enable-subproject $1"
 AC_CONFIG_SUBDIRS([lol])
 AC_SUBST(lol_srcdir, '${top_srcdir}/lol')
 AC_SUBST(lol_builddir, '${top_builddir}/lol')

configure.ac

@@ -84,6 +84,8 @@ AC_ARG_ENABLE(ffmpeg,
   [  --enable-ffmpeg         build using FFmpeg (default autodetected)])
 AC_ARG_ENABLE(sdl,
   [  --enable-sdl            build using SDL (default autodetected)])
+AC_ARG_ENABLE(imlib2,
+  [  --enable-imlib2         build using Imlib2 (default autodetected)])
 
 AC_ARG_ENABLE(test,
   [  --enable-test           build test suite (default yes)])