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/a.out.h b/arch/x86/include/asm/a.out.h
index 0948748..4684f97 100644
--- a/arch/x86/include/asm/a.out.h
+++ b/arch/x86/include/asm/a.out.h
@@ -1,5 +1,5 @@
-#ifndef ASM_X86__A_OUT_H
-#define ASM_X86__A_OUT_H
+#ifndef _ASM_X86_A_OUT_H
+#define _ASM_X86_A_OUT_H
 
 struct exec
 {
@@ -17,4 +17,4 @@
 #define N_DRSIZE(a)	((a).a_drsize)
 #define N_SYMSIZE(a)	((a).a_syms)
 
-#endif /* ASM_X86__A_OUT_H */
+#endif /* _ASM_X86_A_OUT_H */