add option to disable setting the system clock on boot for linux systems

This commit adds the clock_hctosys option which is used to skip setting
the system clock on boot and can be used with a modern linux kernel
which has the CONFIG_RTC_HCTOSYS option set to y.
I would like to thank Dimitris Mandalidis for the report and for the
patch to baselayout-1 on which my changes to openrc are based.

X-Gentoo-Bug: 248131
X-Gentoo-Bug-URL: http://bugs.gentoo.org/show_bug.cgi?id=248131

conf.d/hwclock

@@ -9,6 +9,14 @@ clock="UTC"
 # You normally don't need to do this if you run a ntp daemon.
 clock_systohc="NO"
 
+# If you want to set the system time to the current hardware clock
+# during bootup, then say "YES" here. You do not need this if you are
+# running a modern kernel with CONFIG_RTC_HCTOSYS set to y.
+# Also, be aware that if you set this to "NO", the system time will
+# never be saved to the hardware clock unless you set
+# clock_systohc="YES" above.
+clock_hctosys="YES"
+ 
 # If you wish to pass any other arguments to hwclock during bootup,
 # you may do so here. Alpha users may wish to use --arc or --srm here.
 clock_args=""

init.d/hwclock.in

@@ -64,6 +64,7 @@ _hwclock()
 
 start()
 {
+	yesno $clock_hctosys || return 0
 	local retval=0 errstr=""
 	setupopts