um: Disable CONFIG_GCOV with MODULES

CONFIG_GCOV doesn't work with modules, and for various reasons
it cannot work, see also
https://lore.kernel.org/r/d36ea54d8c0a8dd706826ba844a6f27691f45d55.camel@sipsolutions.net

Make CONFIG_GCOV depend on !MODULES to avoid anyone
running into issues there. This also means we need
not export the gcov symbols.
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Richard Weinberger <richard@nod.at>

arch/um/Kconfig.debug

@@ -17,6 +17,7 @@ config GCOV
 	bool "Enable gcov support"
 	depends on DEBUG_INFO
 	depends on !KCOV
+	depends on !MODULES
 	help
 	  This option allows developers to retrieve coverage data from a UML
 	  session.

arch/um/kernel/Makefile

@@ -21,7 +21,6 @@ obj-y = config.o exec.o exitcode.o irq.o ksyms.o mem.o \
 
 obj-$(CONFIG_BLK_DEV_INITRD) += initrd.o
 obj-$(CONFIG_GPROF)	+= gprof_syms.o
-obj-$(CONFIG_GCOV)	+= gmon_syms.o
 obj-$(CONFIG_EARLY_PRINTK) += early_printk.o
 obj-$(CONFIG_STACKTRACE) += stacktrace.o
 

arch/um/kernel/gmon_syms.c

-// SPDX-License-Identifier: GPL-2.0
-/*
- * Copyright (C) 2001 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
- */
-
-#include <linux/module.h>
-
-extern void __bb_init_func(void *)  __attribute__((weak));
-EXPORT_SYMBOL(__bb_init_func);
-
-extern void __gcov_init(void *)  __attribute__((weak));
-EXPORT_SYMBOL(__gcov_init);
-extern void __gcov_merge_add(void *, unsigned int)  __attribute__((weak));
-EXPORT_SYMBOL(__gcov_merge_add);
-extern void __gcov_exit(void)  __attribute__((weak));
-EXPORT_SYMBOL(__gcov_exit);