Disable gdbserver on host != target configurations

Correct fallout from commit 919adfe84092 ("Move gdbserver to top level")
and revert to not building `gdbserver' in a cross-configuration, that is
where host != target, matching the documented behaviour.  We have no way
to support non-native `gdbserver', and native `gdbserver' is usually of
no use with cross-GDB of the chosen host.

gdbserver/ChangeLog:
2020-02-12  Maciej W. Rozycki <macro@wdc.com>
	    Pedro Alves  <palves@redhat.com>

	Skip building gdbserver in a cross-configuration.
	* configure.srv: Set $gdbserver_host depending on whether $target
	is $host.  Use $gdbserver_host instead of $host.

1 files changed, 9 insertions, 2 deletions

diff --git a/gdbserver/configure.srv b/gdbserver/configure.srv
index 2e83cbd..375ac0a 100644
--- a/gdbserver/configure.srv
+++ b/gdbserver/configure.srv
@@ -33,9 +33,16 @@ ipa_ppc_linux_regobj="powerpc-32l-ipa.o powerpc-altivec32l-ipa.o powerpc-vsx32l-
 # these files over and over again.
 srv_linux_obj="linux-low.o nat/linux-osdata.o nat/linux-procfs.o nat/linux-ptrace.o nat/linux-waitpid.o nat/linux-personality.o nat/linux-namespaces.o fork-child.o nat/fork-inferior.o"
 
-# Input is taken from the "${host}" variable.
+# Input is taken from the "${host}" and "${target}" variables.
 
-case "${host}" in
+# GDBserver can only debug native programs.
+if test "${target}" = "${host}"; then
+    gdbserver_host=${host}
+else
+    gdbserver_host=
+fi
+
+case "${gdbserver_host}" in
   aarch64*-*-linux*)	srv_tgtobj="linux-aarch64-low.o"
 			srv_tgtobj="$srv_tgtobj nat/aarch64-linux-hw-point.o"
 			srv_tgtobj="$srv_tgtobj linux-aarch32-low.o"