libc/uClibc: add patch to fix fork in threads with ARM EABI

uClibc-0.9.32 requires libgcc_eh.a (for ARM EABI), but only when libubacktrace
is enabled. As this is not the default, provide a workaround to disable linking
with libgcc_eh.a if libubacktrace is not selected.

This will however still break if uClibc is configured to enable libubacktrace,
but it requires a fix in gcc, and we can take care of that later.

Reported-by: Grant Edwards <grant.b.edwards@gmail.com>
Reported-by: Tor Krill <tor@codeknot.com>
Tested-by: Tor Krill <tor@codeknot.com>
Signed-off-by: "Yann E. MORIN" <yann.morin.1998@anciens.enib.fr>

 # Bare metal config options

 ## select BARE_METAL

 ##

 ## help 'Bare metal' refers to those programs that run without any kernel.

 ## help

 ## help You probably want to say 'y' here if you plan to use your compiler

 ## help to build bootloaders. It is not yet suitable to build Linux kernels,

 ## help though, because the APCI stuff relies on the target C library headers

 ## help being available?!?!...