libc/glibc: spelling fixes in the menuconfig help entries

nits:
- fix the spelling of changing.
- 'chose' is the correct past tense.

Signed-off-by: Michael Hope <michael.hope@linaro.org>

 # Compute Alpha-specific values

 CT_DoArchTupleValues () {

     # The architecture part of the tuple:

     CT_TARGET_ARCH="${CT_ARCH}${CT_ARCH_ALPHA_VARIANT}"

 }