target/hppa: Generate illegal instruction exception for 64-bit instructions

target/hppa: Generate illegal instruction exception for 64-bit instructions

Qemu currently emulates a 32-bit CPU only, and crashes with this error
when it faces a 64-bit load (e.g.  "ldd 0(r26),r0") or a 64-bit store
(e.g. "std r26,0(r26)") instruction in the guest:

ERROR:../qemu/tcg/tcg-op.c:2822:tcg_canonicalize_memop: code should not be reached

Add checks for 64-bit sizes and generate an illegal instruction
exception if necessary.

Signed-off-by: Helge Deller <deller@gmx.de>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>