[yocto] [matchbox-wm][PATCH] configure.ac: add lib math for composite enabled builds

[Awais Belal]

The composite enabled builds require lib math to be
present on the linker command line otherwise we get
ld: composite-engine.o: undefined reference to symbol 'exp@@GLIBC_2.2.5'
during compilation.

Signed-off-by: Awais Belal <awais_belal at mentor.com>
---
 configure.ac | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/configure.ac b/configure.ac
index dce82cc..1bc113f 100644
--- a/configure.ac
+++ b/configure.ac
@@ -246,9 +246,11 @@ fi
 dnl ------ Composite -------------------------------------------------------
 
 if test x$enable_composite != xno; then
-  PKG_CHECK_MODULES(COMPO, xcomposite xfixes xdamage xrender, ,
+  PKG_CHECK_MODULES(COMPO, xcomposite xfixes xdamage xrender, have_compo_deps=yes,
 			   AC_MSG_ERROR([*** Required Composite Librays not installed ***]))
-
+  if test x$have_compo_deps = xyes; then
+    COMPO_LIBS="$COMPO_LIBS -lm"
+  fi
   AC_DEFINE(USE_COMPOSITE, [1], [use bleeding enge composite code])
 
 fi
-- 
2.7.4