sparc: Export mcount for Clang-built modules

Clang emits calls to mcount for -pg on sparc64, while the
existing ftrace support only exports the _mcount name. With
FUNCTION_TRACER enabled, modules can therefore keep relocations
against mcount and fail during modpost:

  ERROR: modpost: "mcount" [arch/sparc/kernel/chmc.ko] undefined!

_mcount and mcount are aliases in arch/sparc/lib/mcount.S. Export
the plain mcount alias as well so Clang-built modules can resolve
their profiling call target.

Assisted-by: Codex:GPT-5
Signed-off-by: Rosen Penev <rosenp@gmail.com>
Reviewed-by: Andreas Larsson <andreas@gaisler.com>
Signed-off-by: Andreas Larsson <andreas@gaisler.com>

Author: neheb

arch/sparc/include/asm/asm-prototypes.h

@@ -26,6 +26,7 @@ void *memset(void *s, int c, size_t n);
 typedef int TItype __attribute__((mode(TI)));
 TItype __multi3(TItype a, TItype b);
 void _mcount(void);
+void mcount(void);
 
 s64 __ashldi3(s64, int);
 s64 __lshrdi3(s64, int);

arch/sparc/lib/mcount.S

@@ -21,6 +21,7 @@
 	EXPORT_SYMBOL(_mcount)
 	.globl		mcount
 	.type		mcount,#function
+	EXPORT_SYMBOL(mcount)
 _mcount:
 mcount:
 #ifdef CONFIG_FUNCTION_TRACER