[cheese] Use LT_LIB_M to find the math library

[David King <davidk src gnome org>]

commit 0c55ca363b4475e8f26417a7ddf6933f2c492405
Author: Andreas Henriksson <andreas fatal se>
Date:   Wed Sep 24 16:41:27 2014 +0100

    Use LT_LIB_M to find the math library
    
    libcheese-gtk needs to link with -lm to find the fmod function.

 Makefile.am  |    1 +
 configure.ac |    3 +++
 2 files changed, 4 insertions(+), 0 deletions(-)
---
diff --git a/Makefile.am b/Makefile.am
index c811239..c0f6950 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -87,6 +87,7 @@ libcheese_gtk_la_CPPFLAGS = \
 
 libcheese_gtk_la_LIBADD = \
        libcheese.la \
+       $(LIBM) \
        $(CHEESE_LIBS) \
        $(CHEESE_GTK_LIBS)
 
diff --git a/configure.ac b/configure.ac
index 5afd6f5..77f91dc 100644
--- a/configure.ac
+++ b/configure.ac
@@ -24,6 +24,9 @@ AM_PROG_VALAC([0.23.3])
 LT_PREREQ([2.2])
 LT_INIT([disable-static])
 
+# Find an appropriate libm, for fmod()
+LT_LIB_M
+
 PKG_PROG_PKG_CONFIG([0.24])
 
 AC_SUBST([CHEESE_WFLAGS], ["-Wall -DGSEAL_ENABLE"])