kbuild: thin archives make default for all archs

Make thin archives build the default, but keep the config option
to allow exemptions if any breakage can't be quickly solved.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
diff --git a/Documentation/process/changes.rst b/Documentation/process/changes.rst
index e25d63f..68be1bb 100644
--- a/Documentation/process/changes.rst
+++ b/Documentation/process/changes.rst
@@ -31,7 +31,7 @@
 ====================== ===============  ========================================
 GNU C                  3.2              gcc --version
 GNU make               3.81             make --version
-binutils               2.12             ld -v
+binutils               2.20             ld -v
 util-linux             2.10o            fdformat --version
 module-init-tools      0.9.10           depmod -V
 e2fsprogs              1.41.4           e2fsck -V
@@ -75,10 +75,9 @@
 Binutils
 --------
 
-Linux on IA-32 has recently switched from using ``as86`` to using ``gas`` for
-assembling the 16-bit boot code, removing the need for ``as86`` to compile
-your kernel.  This change does, however, mean that you need a recent
-release of binutils.
+The build system has, as of 4.13, switched to using thin archives (`ar T`)
+rather than incremental linking (`ld -r`) for built-in.o intermediate steps.
+This requires binutils 2.20 or newer.
 
 Perl
 ----