configure: prevent premature HAVE_GLU check

When cairo-gl and mesa-glu are present on the system, autoconf successfully
recognizes both. However, I was wondering why weston-screensaver was not
building since autoconf reported all dependencies were met.

Move the mesa-glu PKG_CHECK before the conditional. Additionally, remove
redundant check for enable_egl, as it is implied when GLU is 'yes.'

Signed-off-by: Joe Konno <joe.konno@intel.com>

configure.ac

@@ -230,10 +230,10 @@ if test x$enable_weston_launch == xyes; then
   WESTON_LAUNCH_LIBS="$WESTON_LAUNCH_LIBS -lpam"
 fi
 
-AM_CONDITIONAL(HAVE_GLU, test "x$have_glu" = "xyes" -a "$xenable_egl" = "xyes")
 if test x$enable_egl = xyes; then
   PKG_CHECK_MODULES(GLU, [glu], [have_glu=yes], [have_glu=no])
 fi
+AM_CONDITIONAL(HAVE_GLU, test "x$have_glu" = "xyes")
 
 
 AM_CONDITIONAL(HAVE_POPPLER, test "x$have_poppler" = "xyes")