Add comments about the BUILD_NATIVE change

This is a significant change and mention of it should have gone into
UPGRADE.txt and CHANGES.


git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/1.8@370081 65c4cc65-6c06-0410-ace0-fbb531ad65f3

CHANGES

@@ -8,6 +8,18 @@
 ===
 ======================================================================
 
+------------------------------------------------------------------------------
+--- Functionality changes since Asterisk 1.8.12.0 ----------------------------
+------------------------------------------------------------------------------
+
+Build System
+------------
+ * The optimization portion of the build system has been reworked to avoid
+   broken builds on certain architectures.  All architecture-specific
+   optimization has been removed in favor of using -march=native to allow gcc
+   to detect the environment in which it is running when possible.  This can
+   be toggled as BUILD_NATIVE under "Compiler Flags" in menuselect.
+
 ------------------------------------------------------------------------------
 --- Functionality changes since Asterisk 1.8.10.0 ----------------------------
 ------------------------------------------------------------------------------

UPGRADE.txt

@@ -18,6 +18,11 @@
 ===
 ===========================================================
 
+From 1.8.12 to 1.8.13:
+* The complex processor detection and optimization has been removed from
+  the makefile in favor of using native optimization suppport when available.
+  BUILD_NATIVE can be disabled via menuselect under "Compiler Flags".
+
 From 1.8.11 to 1.8.12:
 * In AEL dialplans, the "h" extension will now be inherited from prior
   calling contexts, just as it had in 1.4.  If you have created an AEL