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>

# Compute AVR32-specific values

CT_DoArchTupleValues() {

    # The architecture part of the tuple:

    CT_TARGET_ARCH="${CT_ARCH}"

    # gcc ./configure flags

    CT_ARCH_WITH_ARCH=

    CT_ARCH_WITH_ABI=

    CT_ARCH_WITH_CPU=

    CT_ARCH_WITH_TUNE=

    CT_ARCH_WITH_FPU=

    CT_ARCH_WITH_FLOAT=

    CT_TARGET_SYS=none

}