uclibc, eglibc: remove REALLY_NOSTDLIB references

These were required with ARC gcc 4.4.7; ARC gcc 4.8 has been changed
to behave the same as other architectures with -nostdlib, making this
option obsolete.

Signed-off-by: Mischa Jonker <mjonker@synopsys.com>
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>