GNAT/testsuite: Pass the `ada' option to target compilation

Pass the `ada' option to DejaGNU's `target_compile' procedure, which by
default calls `default_target_compile', so that it arranges for an Ada
compilation rather the default of C.  We set the compiler to `gnatmake'
manually here, so that part of the logic in `default_target_compile' is
not used, but it affects other settings, such as the use of `adaflags'.

	gcc/testsuite/
	* lib/gnat.exp (gnat_target_compile): Pass the `ada' option to
	`target_compile'.

From-SVN: r276085

gcc/testsuite/ChangeLog

+2019-09-23  Maciej W. Rozycki  <macro@wdc.com>
+
+	* lib/gnat.exp (gnat_target_compile): Pass the `ada' option to
+	`target_compile'.
+
 2019-09-23  Paolo Carlini  <paolo.carlini@oracle.com>
 
 	* g++.dg/cpp0x/pr68724.C: Check location(s) too.

gcc/testsuite/lib/gnat.exp

@@ -167,6 +167,8 @@ proc gnat_target_compile { source dest type options } {
 	set options [concat "additional_flags=$TOOL_OPTIONS" $options]
     }
 
+    set options [concat "{ada}" $options]
+
     return [target_compile $source $dest $type $options]
 }