Drop some straggling mentions of gcc-4.9 as being stale

Fix up the admin-guide README file to the new gcc-5.1 requirement, and
remove a stale comment about gcc support for the __assume_aligned__
attribute.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Documentation/admin-guide/README.rst

@@ -259,7 +259,7 @@ Configuring the kernel
 Compiling the kernel
 --------------------
 
- - Make sure you have at least gcc 4.9 available.
+ - Make sure you have at least gcc 5.1 available.
    For more information, refer to :ref:`Documentation/process/changes.rst <changes>`.
 
    Please note that you can still run a.out user programs with this kernel.

Documentation/translations/zh_CN/admin-guide/README.rst

@@ -223,7 +223,7 @@ Linux内核5.x版本 <http://kernel.org/>
 编译内核
 ---------
 
- - 确保您至少有gcc 4.9可用。
+ - 确保您至少有gcc 5.1可用。
    有关更多信息，请参阅 :ref:`Documentation/process/changes.rst <changes>` 。
 
    请注意，您仍然可以使用此内核运行a.out用户程序。

Documentation/translations/zh_TW/admin-guide/README.rst

@@ -226,7 +226,7 @@ Linux內核5.x版本 <http://kernel.org/>
 編譯內核
 ---------
 
- - 確保您至少有gcc 4.9可用。
+ - 確保您至少有gcc 5.1可用。
    有關更多信息，請參閱 :ref:`Documentation/process/changes.rst <changes>` 。
 
    請注意，您仍然可以使用此內核運行a.out用戶程序。

include/linux/compiler_attributes.h

@@ -54,7 +54,6 @@
  * compiler should see some alignment anyway, when the return value is
  * massaged by 'flags = ptr & 3; ptr &= ~3;').
  *
- * Optional: only supported since gcc >= 4.9
  * Optional: not supported by icc
  *
  *   gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-assume_005faligned-function-attribute