cairo: fix build issue with gcc 4.9

Fix build with gcc 4.9

cairo fails to build with gcc 4.9 due to a bad interaction of cairo

modules with the LTO mechanism. The suggested workaround is to pass

-ffat-lto-objects. See

https://bugs.freedesktop.org/show_bug.cgi?id=77060 for the upstream

bug report, and

https://bugs.archlinux.org/task/40313?project=1&openedfrom=-1+week for

the ArchLinux bug report.

This patch passes -ffat-lto-objects when gcc understands this option,

in order to provide compatibility with gcc versions older than 4.8,

which did not provide this option, but are anyway unaffected by the

issue.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

Index: b/configure.ac

===================================================================

--- a/configure.ac

+++ b/configure.ac

@@ -37,6 +37,16 @@

 m4_include(build/configure.ac.pthread)  dnl checks for pthreads

 AC_CACHE_SAVE

+old_cflags=$CFLAGS

+CFLAGS=-ffat-lto-objects

+AC_MSG_CHECKING([whether CC supports -ffat-lto-objects])

+AC_COMPILE_IFELSE([AC_LANG_PROGRAM([])],

+    [AC_MSG_RESULT([yes])]

+    [LTO_CFLAGS=-ffat-lto-objects],

+    [AC_MSG_RESULT([no])]

+)

+CFLAGS="${old_CFLAGS} ${LTO_CFLAGS}"

+

 dnl ===========================================================================

 AC_CHECK_LIB(z, compress,

CAIRO_LICENSE_FILES = COPYING

CAIRO_SITE = http://cairographics.org/releases

CAIRO_INSTALL_STAGING = YES

CAIRO_AUTORECONF = YES

CAIRO_CONF_ENV = ac_cv_func_posix_getpwuid_r=yes glib_cv_stack_grows=no \

		glib_cv_uscore=no ac_cv_func_strtod=yes \