2009-09-17  Emmanuel Briot  <briot@adacore.com>

	* prj-ext.adb, prj-ext.ads, makeutl.adb (Is_External_Assignment):
	Remove duplicate code.
	(Prj.Ext): Fix memory leak
	(Check): Now allow the syntax "-Xfoo=" to set an empty value to the
	variable. This was previously allowed in the code in
	Is_External_Assignment, and some tests rely on it

From-SVN: r151793