[Ada] Document new switch --copy-environment for gnattest

2018-05-25  Fedor Rybin  <frybin@adacore.com>

gcc/ada/

	* doc/gnat_ugn/gnat_utility_programs.rst: Document new switch
	--copy-environment for gnattest.

From-SVN: r260714

gcc/ada/ChangeLog

+2018-05-25  Fedor Rybin  <frybin@adacore.com>
+
+	* doc/gnat_ugn/gnat_utility_programs.rst: Document new switch
+	--copy-environment for gnattest.
+
 2018-05-24  Piotr Trojanek  <trojanek@adacore.com>
 
 	* sem_elab.adb (Non_Private_View): Simplify by removing a local Result

gcc/ada/doc/gnat_ugn/gnat_utility_programs.rst

@@ -4759,6 +4759,13 @@ Alternatively, you may run the script using the following command line:
     Runs ``n`` tests in parallel (default is 1).
 
 
+    .. index:: --copy-environment (gnattest)
+
+  :switch:`--copy-environment={dir}`
+    Contents of ``dir`` directory will be copied to temporary directories
+    created by gnattest in which individual test drivers are spawned.
+
+
   .. _Project_Attributes_for_gnattest:
 
   Project Attributes for ``gnattest``