amd64: dump standard registers when crashing

[mjg]

Summary

Sample output:

Fatal trap 12: page fault while in kernel mode
cpuid = 1; apic id = 01
fault virtual address   = 0x2 
fault code              = supervisor write data, page not present
instruction pointer     = 0x20:0xffffffff80556853
stack pointer           = 0x28:0xffffffff8141bf50
frame pointer           = 0x28:0xffffffff8141bfa0
code segment            = base 0x0, limit 0xfffff, type 0x1b
                        = DPL 0, pres 1, long 1, def32 0, gran 1
processor eflags        = interrupt enabled, resume, IOPL = 0 
current process         = 0 (swapper)
rdi: fffff80002c9c400 rsi: ffffffff80b89183 rdx:                0   
rcx:                2  r8:               fe  r9:                1
rax: fffff80002c9c400 rbx:                1 rbp: ffffffff8141bfa0
r10:                0 r11: ffffffff80b97f8c r12:                0
r13:                0 r14:                0 r15:                0
trap number             = 12
panic: page fault
cpuid = 1 
time = 1

now it is slightly redundant with rip, rsp and rbp being printed twice, but I don't think that's a big deal.

[kib]

sys/amd64/amd64/trap.c

934

I suggest omitting this line, it is clear what is printed, without the header

935

Lines are too long, please wrap them.

[mjg]

• wrap lines
• remove 'register dump' line