Lot of bugfixes in r_asm, x86 assembler and ragg2 -x

- Thanks Ripe for reporting
- Handle $pc in r_asm assemble
- New ops for x86.nz: sar, shl, shr, shl, rcr, rcl, ror, rol
- Fix disassembler indentation for functions
- Fix memory align issue in r_sys_run()