Make BMI2 inline assembly check more robust

Authored by jukivili on Jan 6 2018, 7:26 PM.

Description

Make BMI2 inline assembly check more robust

* configure.ac (gcry_cv_gcc_inline_asm_bmi2): New assembly test.

Use actual assembly snippets from keccak.c to check that compiler
has proper support for used BMI2 instructions.

  • GnuPG-bug-id: T3408
  • Signed-off-by: Jussi Kivilinna <jussi.kivilinna@iki.fi>