Use modified GDB script on Windows.

testsuite/gdbpp/gdbinit.windows

@@ -0,0 +1,31 @@
+set logging redirect on
+set logging file NUL
+set logging enabled on
+# Redirecting of the output to file and enable logging send all GDB's output
+# into the file. Logging is disabled a bit later when output of the
+# 'output'/'echo' commands need to be output to the standard output to check
+# with expected results.
+
+source vss_pp.py
+
+start
+set charset UTF-8
+next
+next
+next
+next
+next
+
+set logging enabled off
+output ss1
+echo \n
+output us1
+echo \n
+output vsn
+echo \n
+output vs1
+echo \n
+output vs2
+echo \n
+output vi1
+echo \n

testsuite/gdbpp/test.sh

@@ -1,2 +1,6 @@
 gprbuild -q -P test.gpr
-gdb --batch --command=gdbinit --directory=$VSS_GDBPP .objs/main
+if [ "$OS" = "Windows_NT" ]; then
+  gdb --batch --command=gdbinit.windows --directory=$VSS_GDBPP .objs/main
+else
+  gdb --batch --command=gdbinit.posix --directory=$VSS_GDBPP .objs/main
+fi