glibc: add more Imagination Meta relocation to elf.h
glibc master added the EM_METAG tag but didn't add the relocation defines.
However the kernel tooling only checks for EM_METAG when defining its own values
so scripts/recordmcount ends up using R_META_* symbols without their definition.
Whilst the kernel can and should be fixed, this breaks all users of recordmcount
so patch elf.h to add the values.
Signed-off-by: Ross Burton <ross.burton@intel.com>
