Don't use a time_t variable with fscanf when parsing uptime

Because "%u" is used as format string in the fscanf call that parses the
uptime and because the length of time_t varies on different platforms
and architectures the value was not written properly if time_t was longer
than an unsigned int and depending on how the target variable was aligned
on the stack.  Since there is no conversion specifier to properly parse a
time_t value we use the appropriate integer type instead.

src/libimcv/os_info/os_info.c

@@ -156,7 +156,7 @@ METHOD(os_info_t, get_uptime, time_t,
 {
 	const char proc_uptime[] = "/proc/uptime";
 	FILE *file;
-	time_t uptime;
+	u_int uptime;
 
 	file = fopen(proc_uptime, "r");
 	if (!file)