gdbserver: fix gdbserver builds after expedite_regs changes

After this commit:

  commit 6a65998a8a94abaaae7ca4ff0ab9c3f25dc2e766
  Date:   Mon Sep 11 12:42:00 2023 +0100

      Convert tdesc's expedite_regs to a string vector

The risc-v, loongarch, and csky gdbserver builds were broken.  A use
of target_desc::expedite_regs (for each architecture)  was not updated
to take account of the type change.

I've tested that this fixes the risc-v build.  I haven't tested the
other architectures, but they should be fine.

3 files changed, 16 insertions, 6 deletions

diff --git a/gdbserver/linux-csky-low.cc b/gdbserver/linux-csky-low.cc
index 3117556..feb428e 100644
--- a/gdbserver/linux-csky-low.cc
+++ b/gdbserver/linux-csky-low.cc
@@ -132,8 +132,11 @@ csky_target::low_arch_setup ()
   static const char *expedite_regs[] = { "r14", "pc", NULL };
   target_desc_up tdesc = csky_create_target_description ();
 
-  if (!tdesc->expedite_regs)
-    init_target_desc (tdesc.get (), expedite_regs);
+  if (tdesc->expedite_regs.empty ())
+    {
+      init_target_desc (tdesc.get (), expedite_regs);
+      gdb_assert (!tdesc->expedite_regs.empty ());
+    }
 
   current_process ()->tdesc = tdesc.release ();
 
diff --git a/gdbserver/linux-loongarch-low.cc b/gdbserver/linux-loongarch-low.cc
index ead2e76..3eb87f5 100644
--- a/gdbserver/linux-loongarch-low.cc
+++ b/gdbserver/linux-loongarch-low.cc
@@ -84,8 +84,11 @@ loongarch_target::low_arch_setup ()
   features.xlen = sizeof (elf_greg_t);
   tdesc = loongarch_create_target_description (features);
 
-  if (!tdesc->expedite_regs)
-    init_target_desc (tdesc.get (), expedite_regs);
+  if (tdesc->expedite_regs.empty ())
+    {
+      init_target_desc (tdesc.get (), expedite_regs);
+      gdb_assert (!tdesc->expedite_regs.empty ());
+    }
   current_process ()->tdesc = tdesc.release ();
 }
 
diff --git a/gdbserver/linux-riscv-low.cc b/gdbserver/linux-riscv-low.cc
index 129bc3b..4c251bb 100644
--- a/gdbserver/linux-riscv-low.cc
+++ b/gdbserver/linux-riscv-low.cc
@@ -90,8 +90,12 @@ riscv_target::low_arch_setup ()
     = riscv_linux_read_features (lwpid_of (current_thread));
   target_desc_up tdesc = riscv_create_target_description (features);
 
-  if (!tdesc->expedite_regs)
-    init_target_desc (tdesc.get (), expedite_regs);
+  if (tdesc->expedite_regs.empty ())
+    {
+      init_target_desc (tdesc.get (), expedite_regs);
+      gdb_assert (!tdesc->expedite_regs.empty ());
+    }
+
   current_process ()->tdesc = tdesc.release ();
 }