Include binaries built directly from @igrr repo

Rebuild the binaries using a git clone of
https://github.com/igrr/newlib-xtensa

Build commands for posterity:
````
rm -rf ./xtensa-lx106-elf/
./configure --prefix=<DIR>/esp8266/tools/sdk/libc --with-newlib \
            --enable-multilib --disable-newlib-io-c99-formats \
            --disable-newlib-supplied-syscalls \
            --enable-newlib-nano-formatted-io --enable-newlib-reent-small \
            --enable-target-optspace \
            --program-transform-name="s&^&xtensa-lx106-elf-&" \
            --disable-option-checking --with-target-subdir=xtensa-lx106-elf \
            --target=xtensa-lx106-elf
rm -f etc/config.cache
CROSS_CFLAGS="-fno-omit-frame-pointer -DSIGNAL_PROVIDED -DABORT_PROVIDED"\
             " -DMALLOC_PROVIDED" \
  PATH=<DIR>/esp8266/tools/xtensa-lx106-elf/bin/:$PATH \
  make all install
````

Author: earlephilhower