Turbostat: Don't include msr-index.h, use standard header
Turbostat: Emphasize the origin of the code
Turbostat: replace stdbool.h with C99 _Bool
Turbostat: expand __must_check macro and remove it
Turbostat: replace sprintf with ssnprintf from common.h
Turbostat: specify parse_int_file format
Turbostat: Don't manage 'Interval' manually, already done by collectd