libc/newlib: cleanup the build and finish steps

build step:
- ./configure
- remove glibc-specific options
- pass the target CFLAGS in the correct variable
- make:
- build in //

finish step:
- print proper message in finish step

reporter_name="Yann E. MORIN"

reporter_url="http://ymorin.is-a-geek.org/dokuwiki/projects/crosstool"

reporter_comment=""