[lightsoff] Revert "build: remove extraneous AC_CHECK_LIB"

[Michael Catanzaro <mcatanzaro src gnome org>]

commit 0d155a6a25a14ec68043fae33db1b5490f47faf6
Author: Michael Catanzaro <mcatanzaro gnome org>
Date:   Sun Nov 3 09:13:54 2013 -0600

    Revert "build: remove extraneous AC_CHECK_LIB"
    
    This reverts commit 0f200f4c3ae66d29c35c843a83d12fb3de98b76e.
    
    These fuctions are actually provided by glibc, not glib. Vala hides them
    in the glib namespace. Lightsoff won't link without this.

 configure.ac |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)
---
diff --git a/configure.ac b/configure.ac
index 0e942cb..5526480 100644
--- a/configure.ac
+++ b/configure.ac
@@ -23,6 +23,8 @@ PKG_CHECK_MODULES(LIGHTSOFF, [
   clutter-gtk-1.0 >= $CLUTTER_REQUIRED
 ])
 
+AC_CHECK_LIB([m],[floor])
+
 AC_PATH_PROG(APPDATA_VALIDATE, appdata-validate)
 AC_PATH_PROG(DESKTOP_FILE_VALIDATE, desktop-file-validate)