arc: libgloss: Use long calls attribute for exit_halt

According to GCC documentation for ARC, a function marked with
the long_call attribute is always called using register-indirect
jump-and-link instructions, thereby enabling the called function
to be placed anywhere within the 32-bit address space.

exit_halt function is provided by crt0.S and it's used
in nsim-syscalls.c. Thus, we want to ensure that a linkage
issue will not arise.

Signed-off-by: Claudiu Zissulescu <claziss@gmail.com>

libgloss/arc/nsim-syscalls.c

@@ -1,5 +1,5 @@
 /*
-   Copyright (c) 2015, Synopsys, Inc. All rights reserved.
+   Copyright (c) 2015-2024, Synopsys, Inc. All rights reserved.
 
    Redistribution and use in source and binary forms, with or without
    modification, are permitted provided that the following conditions are met:
@@ -100,7 +100,7 @@ _open (const char * pathname, int flags, int mode)
 }
 
 /* Should be provided by crt0.S.  */
-extern void __attribute__((noreturn)) _exit_halt ();
+extern void __attribute__((noreturn, long_call)) _exit_halt ();
 
 void
 __attribute__((noreturn))