arm64: Add detection code for broken .inst support in binutils

arm64: Add detection code for broken .inst support in binutils

Binutils version up to (and including) 2.25 have a pathological
behaviour when it comes to mixing .inst directive and arithmetic
involving labels. The assembler complains about non-constant
expressions and compilation stops pretty quickly.

In order to detect this and work around it, let's add a bit of
detection code that will set the CONFIG_BROKEN_GAS_INST option
should a broken gas be detected.

Acked-by: Will Deacon <[email protected]>
Signed-off-by: Marc Zyngier <[email protected]>
Signed-off-by: Catalin Marinas <[email protected]>