Fix 'declaration inside parameter list' warning

Solve "make check-per" failed on Lubuntu

Unify the naming of asn_OCTET_STRING_specifics_t variables

Delete unnecessary checks before some function calls

1. Add forward definition section.
2. Move type definition inside A_SEQUENCE_OF() to forward definition section.
3. Modify asn1c_lang_C_type_CHOICE() ...etc functions to achieve it.
4. Modify test cases used during 'make check'.

Fixed debug logging bug in per_get_few_bits.

'_specifics_t' variables to have 'asn_SPC_' prefix instead of 'asn_DEF_'
prefix.