arm64: Add Armv8.5-A BTI support to assembly files

Add Branch Target Identifiers (BTIs) to all functions defined in AArch64 assembly files.

BTI support is turned on or off at compile time based on the presence of the __ARM_FEATURE_BTI_DEFAULT feature macro.

A binary compiled with BTI support can be executed on an Armv8-A processor without BTI support because the instructions are defined in NOP space.

Signed-off-by: Jonathan Wright jonathan.wright@arm.com Signed-off-by: Matthew Dalzell matthew.dalzell@arm.com Signed-off-by: Salome Thirot salome.thirot@arm.com