Added profiler.h which defines classes and macros for defining profiler
objects. Also added gdb command j6prof for printing profile data. Added
the syscall_profiles profiler class and auto wrapping of syscalls with
profile objects.
Other changes in this commit:
- Made the gdb command `j6threads` argument for specifying a CPU
optional. Without an argument, it loops through all CPUs.
- Switched to -mcmodel=kernel for kernel code, which makes `call`
instructions easier to follow when debugging / looking at disassembly.
a03804b09d