libc/uClibc: normalize uclibc hidden version names

Hidden version names for uClibc conflicted:

LIBC_UCLIBC_V_0_9_30_2
LIBC_V_0_9_30_1

name them constantly as:
LIBC_UCLIBC_V_<version>

Also update the build script where we use snapshots by version or snapshots by date.

Signed-off-by: Bryan Hundven <bryanhundven@gmail.com>

 reporter_name="Ioannis E. VENETIS"

 reporter_url="http://sourceware.org/ml/crossgcc/2009-11/msg00109.html"

 reporter_comment=""