Avoid unaligned access in emit_intX methods if it's unsupported

emit_int16/32/64 use direct memory access in shared code, this may result in unaligned memory stores on platforms where unaligned memory access is disabled by default:
risc-v, arm32
lets use put_native in emit_intXX methods, this will affect next platforms as well:
ppc and x86
we will use properly aligned memory stores in put_native_XX methods only if it is required by global variables.