[gcc r14-7847] gccrs: proc_macro: Delete unused prototype

[Arthur Cohen]

https://gcc.gnu.org/g:ea0bd46eb863542f965b93a8bb02289ae9dd5ac8

commit r14-7847-gea0bd46eb863542f965b93a8bb02289ae9dd5ac8
Author: Pierre-Emmanuel Patry <pierre-emmanuel.patry@embecosm.com>
Date:   Wed Jul 26 18:05:42 2023 +0200

    gccrs: proc_macro: Delete unused prototype
    
    This function prototype was forgotten when the function was deleted.
    
    libgrust/ChangeLog:
    
            * libproc_macro/proc_macro.h (proc_macro_register_from_str):
            Remove rogue function prototype.
    
    Signed-off-by: Pierre-Emmanuel Patry <pierre-emmanuel.patry@embecosm.com>

Diff:
---
 libgrust/libproc_macro/proc_macro.h | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/libgrust/libproc_macro/proc_macro.h b/libgrust/libproc_macro/proc_macro.h
index 60d9fcb75b1..457ec4693f6 100644
--- a/libgrust/libproc_macro/proc_macro.h
+++ b/libgrust/libproc_macro/proc_macro.h
@@ -62,9 +62,6 @@ struct Bang
   const char *name;
   BangMacro macro;
 };
-
-void
-proc_macro_register_from_str (ProcMacro::from_str_function_t fn);
 }
 
 enum ProcmacroTag