[flang] COMPLEX(16) parameters/returns are not supported for aarch64

[vzakhari]

test-suite::gfortran-regression-compile-regression__pr36006-2_f90.test started failing after #83874

It used to report not yet implemented: no math runtime available for 'EXP(COMPLEX(KIND=16))', but this was not considered as failure. Now it fails with

not yet implemented: complex for this precision for return type
LLVM ERROR: aborting

COMPLEX(16) ABI support is needed in

llvm-project/flang/lib/Optimizer/CodeGen/Target.cpp

Line 730 in e77a473

struct TargetAArch64 : public GenericTarget<TargetAArch64> {

[llvmbot]

@llvm/issue-subscribers-flang-ir

Author: Slava Zakharin (vzakhari)

`test-suite::gfortran-regression-compile-regression__pr36006-2_f90.test` started failing after https://github.com//pull/83874

It used to report not yet implemented: no math runtime available for 'EXP(COMPLEX(KIND=16))', but this was not considered as failure. Now it fails with

not yet implemented: complex for this precision for return type
LLVM ERROR: aborting

COMPLEX(16) ABI support is needed in

llvm-project/flang/lib/Optimizer/CodeGen/Target.cpp

Line 730 in e77a473

struct TargetAArch64 : public GenericTarget<TargetAArch64> {