gcc-4.6: Backport fix for PR32219

gcc-4.6: Backport fix for PR32219

This fix is needed for gold to work. Otherwise
connman fails to build since it used hidden weak
symbols.

See

http://gcc.gnu.org/bugzilla/PR32219
http://www.cygwin.com/ml/binutils/2008-02/msg00239.html

The fix proposed to gcc had reviews which were not addressed hence the
patch is not yet
applied to gcc upstream.

connman can also have workaround by changing the visibility of these
symbols to be default
 __attribute__ ((weak, visibility("hidden")))

to

 __attribute__ ((weak, visibility("default")))

in include/plugin.h

Signed-off-by: Khem Raj <raj.khem@gmail.com>