Sanitize gcc version header includes

- include the gcc version-dependent header files from the generic gcc
   header file, rather than the other way around (iow: don't make the
   non-gcc header file have to know about gcc versions)

 - don't include compiler-gcc4.h for gcc 5 (for whenever it gets
   released).  That's just confusing and made us do odd things in the
   gcc4 header file (testing that we really had version 4!)

 - generate the name from the __GNUC__ version directly, rather than
   having a mess of #if conditionals.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

include/linux/compiler-gcc.h

@@ -61,3 +61,8 @@
 #define  noinline			__attribute__((noinline))
 #define __attribute_const__		__attribute__((__const__))
 #define __maybe_unused			__attribute__((unused))
+
+#define __gcc_header(x) #x
+#define _gcc_header(x) __gcc_header(linux/compiler-gcc##x.h)
+#define gcc_header(x) _gcc_header(x)
+#include gcc_header(__GNUC__)

include/linux/compiler-gcc3.h

@@ -2,9 +2,6 @@
 #error "Please don't include <linux/compiler-gcc3.h> directly, include <linux/compiler.h> instead."
 #endif
 
-/* These definitions are for GCC v3.x.  */
-#include <linux/compiler-gcc.h>
-
 #if __GNUC_MINOR__ >= 3
 # define __used			__attribute__((__used__))
 #else

include/linux/compiler-gcc4.h

@@ -2,9 +2,6 @@
 #error "Please don't include <linux/compiler-gcc4.h> directly, include <linux/compiler.h> instead."
 #endif
 
-/* These definitions are for GCC v4.x.  */
-#include <linux/compiler-gcc.h>
-
 #define __used			__attribute__((__used__))
 #define __must_check 		__attribute__((warn_unused_result))
 #define __compiler_offsetof(a,b) __builtin_offsetof(a,b)
@@ -16,7 +13,7 @@
  */
 #define uninitialized_var(x) x = x
 
-#if !(__GNUC__ == 4 && __GNUC_MINOR__ < 3)
+#if __GNUC_MINOR__ >= 3
 /* Mark functions as cold. gcc will assume any path leading to a call
    to them will be unlikely.  This means a lot of manual unlikely()s
    are unnecessary now for any paths leading to the usual suspects

include/linux/compiler.h

@@ -36,12 +36,8 @@ extern void __chk_io_ptr(const volatile void __iomem *);
 
 #ifdef __KERNEL__
 
-#if __GNUC__ >= 4
-# include <linux/compiler-gcc4.h>
-#elif __GNUC__ == 3 && __GNUC_MINOR__ >= 2
-# include <linux/compiler-gcc3.h>
-#else
-# error Sorry, your compiler is too old/not recognized.
+#ifdef __GNUC__
+#include <linux/compiler-gcc.h>
 #endif
 
 #define notrace __attribute__((no_instrument_function))