On Solaris uptime was wrong, fix it to read the proper kstat statistic.
Added two ways to compute uptime on UNIX.

Tested on Linux and Solaris 9.
Fix typo, it existed there a long time causing configure test to always fail.
Fix dependencies for sysinfo_test.
map_test is overly slow on old platforms, speedup by avoid calling memcpy a million times.
Print uptime in sysinfo_test so that it can be verified visually.
Convert sprintf calls to snprintf.
Clean up whitespace mess in sysinfo.c.