elf: Remove loading legacy hwcaps/platform entries in dynamic loader

elf: Remove loading legacy hwcaps/platform entries in dynamic loader

The legacy hwcaps mechanism was removed with glibc 2.37:
See this commit series:
- d178c67535f0d159df73843e7c18cbdb39b4d25d
x86_64: Remove platform directory library loading test
- 6099908fb84debee4c3bcb05d88769410c2aecd1
elf: Remove legacy hwcaps support from the dynamic loader
- b78ff5a25dc8ba9d8c6df10bb0a533254bdd193f
elf: Remove legacy hwcaps support from ldconfig
- 4a7094119ce05cadf927f52cc5d723e2195e65f9
elf: Remove hwcap parameter from add_to_cache signature
- cfbf883db36727a84ef7929af49ef68c195b5972
elf: Remove hwcap and bits_hwcap fields from struct cache_entry
- 78d9a1620b840deb0880686e4159eaf70708866a
Add NEWS entry for legacy hwcaps removal
- ab40f20364f4a417a63dd51fdd943742070bfe96
elf: Remove _dl_string_hwcap
- e76369ed6371734f77f468eab097ef4e5b5db1c5
elf: Simplify output of hwcap subdirectories in ld.so help

According to Florian Weimer, this was an oversight and should also
have been removed.

As ldconfig does not generate ld.so.cache entries with hwcap/platform
bits in the hwcap-field anymore, this patch now skips those entries.
Thus currently only named-hwcap-entries and the default entries are
allowed.
For named-hwcap entries bit 62 is set and also the isa-level bits can
be set.
For the default entries the hwcap-field is 0.
Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>