adt-manual, ref-manual: Cross-toolchain details added. New class also.

In the adt-manual in the "Optionally Building a Toolchain Installer"
setion, I added some basic advantage information for building a
toolchain installer using bitbake image -c populate_sdk.

In the ref-manual, I added cross-referencing to this basic information
in several strategic areas: "SDK Generation", the populate_sdk class
reference section, the populate_sdk_* class reference section, and the
"Cross-Development Toolchain Generation" sections.

Finally, I also put in documentation for a new class called
autotools-brokensep.

(From yocto-docs rev: cde7dd2fbd7bdc0d71dc678ee7a5422459654287)

Signed-off-by: Scott Rifenbark <scott.m.rifenbark@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

documentation/ref-manual/technical-details.xml

@@ -327,9 +327,22 @@
                 <link linkend='var-SDKMACHINE'><filename>SDKMACHINE</filename></link>,
                 this tool
                 produces executable code that runs on the target device.
+                Only one cross-canadian compiler is produced per architecture
+                since they can be targeted at different processor optimizations
+                using configurations passed to the compiler through the
+                compile commands.
+                This saves the need to have multiple compilers present and
+                hence reduces the size of the toolchains.
                 </para></listitem>
         </itemizedlist>
     </para>
+
+    <note>
+        For information on advantages gained when building a
+        cross-development toolchain installer, see the
+        "<ulink url='&YOCTO_DOCS_ADT_URL;#optionally-building-a-toolchain-installer'>Optionally Building a Toolchain Installer</ulink>"
+        section in the Yocto Project Application Developer's Guide.
+    </note>
 </section>
 
 <section id="shared-state-cache">