[Ada] Document gnatpp's --spaces-only switch

2019-07-11  Bob Duff  <duff@adacore.com>

gcc/ada/

	* doc/gnat_ugn/gnat_utility_programs.rst: Document gnatpp's
	--spaces-only switch.

From-SVN: r273390

gcc/ada/ChangeLog

+2019-07-11  Bob Duff  <duff@adacore.com>
+
+	* doc/gnat_ugn/gnat_utility_programs.rst: Document gnatpp's
+	--spaces-only switch.
+
 2019-07-11  Hristian Kirtchev  <kirtchev@adacore.com>
 
 	* sem_util.adb (Null_Status): Assume that an erroneous construct

gcc/ada/doc/gnat_ugn/gnat_utility_programs.rst

@@ -3257,6 +3257,12 @@ Alternatively, you may run the script using the following command line:
      Keep the line breaks from the source; do not insert or delete any
      line breaks.
 
+   .. index:: --spaces-only (gnatpp)
+
+   :switch:`--spaces-only`
+     Disable all formatting except for inserting and removing spaces.
+     This implies --source-line-breaks.
+
    The ``--comments`` switches are compatible with one another, except
    that the ``--comments-unchanged`` switch disables all other comment
    formatting switches.