overlays/mtk: Fix linker API

The name of the rmap array changed in upstream bintuils commit
2b16913cdca2 ("gdb: make gdbarch_alloc take ownership of the tdep").
At the same time it seems like the xtensa_tdep definition (which
contra the filename is actually a C++ object definition and not a
function prototype!) moved into this file from elsewhere in binutils.

The xtensa_rmap symbol is only used by newer binutils versions than
the Zephyr SDK builds, but add an alias so it builds with upstream
crosstools-ng, and commit it here as a reference if we want to port
the other Xtensa overlays.

Signed-off-by: Andy Ross <andyross@google.com>

overlays/xtensa_mtk_mt818x_adsp/gdb/gdb/xtensa-config.c

@@ -555,7 +555,9 @@ xtensa_register_t rmap[] =
   XTREG_END
 };
 
+extern xtensa_register_t xtensa_rmap[] __attribute__((alias("rmap")));
 
+xtensa_gdbarch_tdep xtensa_tdep (rmap);
 
 #ifdef XTENSA_CONFIG_INSTANTIATE
 XTENSA_CONFIG_INSTANTIATE(rmap,16)

overlays/xtensa_mtk_mt8195_adsp/gdb/gdb/xtensa-config.c

@@ -113,7 +113,7 @@ const xtensa_mask_t xtensa_mask39 = { 1, xtensa_submask39 };
 
 
 /* Register map.  */
-static xtensa_register_t rmap[] =
+xtensa_register_t rmap[] =
 {
   /*    idx ofs bi sz al targno  flags cp typ group name  */
   XTREG(  0,  0,32, 4, 4,0x0020,0x0006,-2, 9,0x2100,pc,          0,0,0,0,0,0)
@@ -496,4 +496,6 @@ static xtensa_register_t rmap[] =
   XTREG_END
 };
 
+extern xtensa_register_t xtensa_rmap[] __attribute__((alias("rmap")));
+
 xtensa_gdbarch_tdep xtensa_tdep (rmap);

overlays/xtensa_mtk_mt8196_adsp/gdb/gdb/xtensa-config.c

@@ -555,7 +555,9 @@ xtensa_register_t rmap[] =
   XTREG_END
 };
 
+extern xtensa_register_t xtensa_rmap[] __attribute__((alias("rmap")));
 
+xtensa_gdbarch_tdep xtensa_tdep (rmap);
 
 #ifdef XTENSA_CONFIG_INSTANTIATE
 XTENSA_CONFIG_INSTANTIATE(rmap,16)