Some targets have a GLIBC_2.0 baseline for libdl, while using
GLIBC_2.2 for libc. This means that the generated libc.map file
does not have any version nodes for GLIBC_2.0 or GLIBC_2.1. However,
moving symbols from libdl into libc needs such version nodes.
(Future symbol moves from librt will need this as well.)
This kludge is only necessary for symbols predating GLIBC_2.2 because
the affected targets use GLIBC_2.2 as the baseline for libc. Given
the small number and fixed set of affected architectures, no generic
mechanism is implemented, and instead the map file fragment is
hard-coded in scripts/versions.mk.
The compat_symbol macro already emits the appropriate version strings,
so no adjustments are needed there.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>