uclibc: fix duplicate vfork problems when static linking

Reported on uClibc mailinglist by Thomas Petazzoni
Should fix:
* SuperH
 http://autobuild.buildroot.org/results/a81/a810c2f27dee1978808461c05cbdcbf51a214e09/build-end.log
* i386
 http://autobuild.buildroot.org/results/f83/f83b65bfc6ea7c7406a02e92afda43e4c5db6e7c/build-end.log
* x86-64
 http://autobuild.buildroot.org/results/64f/64f418f54885e8b5093dc8949c2d1d1ff3c938ea/build-end.log
* powerpc
 http://autobuild.buildroot.org/results/d5b/d5b7ac84dde0e4e26cd7cc46d79e66c39ed5cd53/build-end.log



Tested with i386 static build of alsa-utils.
Patch will be send to uClibc soon, need to finish test-suite run.

Signed-off-by: Waldemar Brodkorb <wbx@openadk.org>
Tested-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>