Commit Briefs
add Linux support for ostatus, fix SigAction struct, and make Makefile portable (main)
The SigAction struct had the wrong layout for Linux (sigset_t is 128 bytes, not 4), which would cause memory corruption. ostatus now reads CPU from /proc/stat, memory from /proc/meminfo, and battery from /sys/class/power_supply/ on Linux. Makefile auto-detects doas or sudo.
