x86: Fix ASM_X86__ header guards

Change header guards named "ASM_X86__*" to "_ASM_X86_*" since:

a. the double underscore is ugly and pointless.
b. no leading underscore violates namespace constraints.

Signed-off-by: H. Peter Anvin <hpa@zytor.com>
diff --git a/arch/x86/include/asm/siginfo.h b/arch/x86/include/asm/siginfo.h
index 808bdfb..fc1aa55 100644
--- a/arch/x86/include/asm/siginfo.h
+++ b/arch/x86/include/asm/siginfo.h
@@ -1,5 +1,5 @@
-#ifndef ASM_X86__SIGINFO_H
-#define ASM_X86__SIGINFO_H
+#ifndef _ASM_X86_SIGINFO_H
+#define _ASM_X86_SIGINFO_H
 
 #ifdef __x86_64__
 # define __ARCH_SI_PREAMBLE_SIZE	(4 * sizeof(int))
@@ -7,4 +7,4 @@
 
 #include <asm-generic/siginfo.h>
 
-#endif /* ASM_X86__SIGINFO_H */
+#endif /* _ASM_X86_SIGINFO_H */