* frontend.adb: Move call to Check_Unused_Withs from Frontend, so
	that it happens before modification of Sloc values for -gnatD.

	* gnat1drv.adb: Move call to Check_Unused_Withs to Frontend,
	so that it happens before modification of Sloc values for -gnatD.

	* switch.adb: Minor reformatting

From-SVN: r48124