x86: remove "extern" from function prototypes in <asm/proto.h>

Function prototypes don't need "extern", and it is generally frowned
upon to have them.
Signed-off-by: NH. Peter Anvin <hpa@zytor.com>

arch/x86/include/asm/proto.h

@@ -5,19 +5,19 @@
 
 /* misc architecture specific prototypes */
 
-extern void early_idt_handler(void);
+void early_idt_handler(void);
 
-extern void system_call(void);
-extern void syscall_init(void);
+void system_call(void);
+void syscall_init(void);
 
-extern void ia32_syscall(void);
-extern void ia32_cstar_target(void);
-extern void ia32_sysenter_target(void);
+void ia32_syscall(void);
+void ia32_cstar_target(void);
+void ia32_sysenter_target(void);
 
-extern void syscall32_cpu_init(void);
+void syscall32_cpu_init(void);
 
-extern void x86_configure_nx(void);
-extern void x86_report_nx(void);
+void x86_configure_nx(void);
+void x86_report_nx(void);
 
 extern int reboot_force;