toolchain/gcc: .init and .fini need to pick one ISA

The .init and .fini sections are built by concatenating code
fragments. Putting mips16 code in the middle of a mips32 code block
doesn't work. Make gcc built the magic crt stuff in no-mips16 mode.

This is specific to 4.6-linaro but is probably portable to other gcc
flavors. Adding this to the t-libgcc-mips16 makefile fragment is a
hack not suitable for pushing upstream, but there is no mips/t-linux
or mips/t-uclibc and I am not going to touch gcc/configure for two
lines.

Signed-off-by: Jay Carlson <nop@nop.com>
Signed-off-by: Florian Fainelli <florian@openwrt.org>

SVN-Revision: 36200