kbuild: remove CONFIG_HAVE_UNDERSCORE_SYMBOL_PREFIX

CONFIG_HAVE_UNDERSCORE_SYMBOL_PREFIX was selected by BLACKFIN, METAG.
They were removed by commit 4ba66a97 ("arch: remove blackfin port"),
commit bb6fb6df ("metag: Remove arch/metag/"), respectively.

No more architecture enables CONFIG_HAVE_UNDERSCORE_SYMBOL_PREFIX.
Clean up the rest of scripts, and remove the Kconfig entry.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: Sam Ravnborg <sam@ravnborg.org>

arch/Kconfig

@@ -686,12 +686,6 @@ config MODULES_USE_ELF_REL
 	  Modules only use ELF REL relocations.  Modules with ELF RELA
 	  relocations will give an error.
 
-config HAVE_UNDERSCORE_SYMBOL_PREFIX
-	bool
-	help
-	  Some architectures generate an _ in front of C symbols; things like
-	  module loading and assembly files need to know about this.
-
 config HAVE_IRQ_EXIT_ON_IRQ_STACK
 	bool
 	help

scripts/Makefile.build

@@ -485,15 +485,10 @@ targets += $(lib-target)
 
 dummy-object = $(obj)/.lib_exports.o
 ksyms-lds = $(dot-target).lds
-ifdef CONFIG_HAVE_UNDERSCORE_SYMBOL_PREFIX
-ref_prefix = EXTERN(_
-else
-ref_prefix = EXTERN(
-endif
 
 quiet_cmd_export_list = EXPORTS $@
 cmd_export_list = $(OBJDUMP) -h $< | \
-	sed -ne '/___ksymtab/s/.*+\([^ ]*\).*/$(ref_prefix)\1)/p' >$(ksyms-lds);\
+	sed -ne '/___ksymtab/s/.*+\([^ ]*\).*/EXTERN(\1)/p' >$(ksyms-lds);\
 	rm -f $(dummy-object);\
 	echo | $(CC) $(a_flags) -c -o $(dummy-object) -x assembler -;\
 	$(LD) $(ld_flags) -r -o $@ -T $(ksyms-lds) $(dummy-object);\

scripts/adjust_autoksyms.sh

@@ -61,9 +61,6 @@ for mod in "$MODVERDIR"/*.mod; do
 	sed -n -e '3{s/ /\n/g;/^$/!p;}' "$mod"
 done | sort -u |
 while read sym; do
-	if [ -n "$CONFIG_HAVE_UNDERSCORE_SYMBOL_PREFIX" ]; then
-		sym="${sym#_}"
-	fi
 	echo "#define __KSYM_${sym} 1"
 done >> "$new_ksyms_file"