app/testpmd: fix build with musl

app/testpmd: fix build with musl

1/ Improve portability by avoiding use of non-standard 'uint'.
Use uint8_t for hash_key_len as rss_key_len is a uint8_t type.
This solves following build error when building with musl libc:
    app/test-pmd/testpmd.h:813:29: error: unknown type name 'uint'

2/ In musl libc, stdout is of type (FILE * const).
Because of the const qualifier, a dark magic cast
must be achieved through uintptr_t.

Fixes: 8205e241b2b0 ("app/testpmd: add missing type to RSS hash commands")
Fixes: e977e4199a8d ("app/testpmd: add commands to load/unload BPF filters")
Cc: stable@dpdk.org
Signed-off-by: Natanael Copa <ncopa@alpinelinux.org>
Reviewed-by: Morten Brørup <mb@smartsharesystems.com>
Signed-off-by: Thomas Monjalon <thomas@monjalon.net>
Acked-by: Andrew Rybchenko <andrew.rybchenko@oktetlabs.ru>
Acked-by: David Marchand <david.marchand@redhat.com>