__clear_cache is defined in lib-arm64.c with a single call to
__arm64_clear_cache, which is the real built-in function and is
turned into inline assembler by gen_clear_cache in arm64-gen.c
More precisely, treat (0 << x) and so on as constant expressions, but
not if const_wanted as we do not want to allow "case (x*0):", ...
Do not optimise (0 / x) and (0 % x) here as x might be zero, though
for an architecture that does not generate an exception for division
by zero the back end might choose to optimise those.
libtcc.c: Add greloca, a generalisation of greloc that takes an addend.
tcc.h: Add greloca and put_elf_reloca.
tccelf.c: Add put_elf_reloca, a generalisation of put_elf_reloc.
tccgen.c: On x86_64, use greloca instead of greloc in init_putv.
The back end functions gen_op(comparison) and gtst() might allocate
registers so case_reg should be left on the value stack while they
are called and set again afterwards.
