x86: fix asm/e820.h for userspace inclusion (again)

asm-x86/e820.h is included from userspace. 'x86: make e820.c to have common functions' (b79cd8f1268bab57ff85b19d131f7f23deab2dee) broke it:

make -C Documentation/lguest
cc -Wall -Wmissing-declarations -Wmissing-prototypes -O3 -I../../include
lguest.c -lz -o lguest

	In file included from ../../include/asm-x86/bootparam.h:8,
	                 from lguest.c:45:
	../../include/asm/e820.h:66: error: expected ‘)’ before ‘start’
	../../include/asm/e820.h:67: error: expected ‘)’ before ‘start’
	../../include/asm/e820.h:68: error: expected ‘)’ before ‘start’
	../../include/asm/e820.h:72: error: expected ‘=’, ‘,’, ‘;’, ‘asm’ 
or ‘__attribute__’ before ‘e820_update_range’
	...

diff -r 0322ce52818b include/asm-x86/e820.h
@@ -59,6 +59,7 @@ struct e820map {
 	struct e820entry map[E820_X_MAX];
 };
 
+#ifdef __KERNEL__
 /* see comment in arch/x86/kernel/e820.c */
 extern struct e820map e820;
 extern struct e820map e820_saved;

@@ -115,7 +116,7 @@ extern char *default_machine_specific_me
 extern char *default_machine_specific_memory_setup(void);
 extern char *machine_specific_memory_setup(void);
 extern char *memory_setup(void);
-
+#endif /* __KERNEL__ */
 #endif /* __ASSEMBLY__ */
 
 #define ISA_START_ADDRESS	0xa0000

applied to tip/x86/urgent, thanks Rusty.

Ingo