Enable tunables by default

All of the major architectures are adopting tunables as a way to add
tuning to the library, from hwcap_mask for aarch64 to HLE for s390 and
ifunc and cache geometry for x86.  Given this adoption and the fact
that we don't want additional tuning knobs to be added outside of
tunables, it makes sense to enable tunables by default using this
trivial patch.

Smoke tested on x86 to ensure that tunables code was built without
specifying it as a configure flag.  I have kept it as --enabled and
not changed it to --disable since we want to still keep the option of
different kinds of front-ends for tunables.

	* configure.ac(--enable-tunables): Enable by default.
	* configure: Regenerate.
	* NEWS: Mention change.
	* manual/install.texi (enable-tunables): Adjust documentation.
	* INSTALL: Regenerate.

1 files changed, 3 insertions, 0 deletions

diff --git a/NEWS b/NEWS
index 8d35bd6c95..804c1b92e6 100644
--- a/NEWS
+++ b/NEWS
@@ -95,6 +95,9 @@ Version 2.26
   as atomic variables to try to implement Dekker's mutual exclusion
   algorithm).
 
+* The tunables feature is now enabled by default.  This allows users to tweak
+  behavior of the GNU C Library using the GLIBC_TUNABLES environment variable.
+
 Security related changes:
 
 * The DNS stub resolver limits the advertised UDP buffer size to 1200 bytes,