clang-format: Add option to always break after a function's return type.

This is required for GNU coding style, among others.

Also update the configuration documentation.

Modified from an original patch by Jarkko Hietaniemi, thank you!

llvm-svn: 214858
diff --git a/clang/docs/ClangFormatStyleOptions.rst b/clang/docs/ClangFormatStyleOptions.rst
index 07febaf..470db9d 100644
--- a/clang/docs/ClangFormatStyleOptions.rst
+++ b/clang/docs/ClangFormatStyleOptions.rst
@@ -133,6 +133,13 @@
   If ``true``, ``while (true) continue;`` can be put on a
   single line.
 
+**AlwaysBreakAfterDefinitionReturnType** (``bool``)
+  If ``true``, always break after function definition return types.
+
+  More truthfully called 'break before the identifier following the type
+  in a function definition'. PenaltyReturnTypeOnItsOwnLine becomes
+  irrelevant.
+
 **AlwaysBreakBeforeMultilineStrings** (``bool``)
   If ``true``, always break before multiline string literals.
 
@@ -158,7 +165,7 @@
     Like ``Attach``, but break before braces on function, namespace and
     class definitions.
   * ``BS_Stroustrup`` (in configuration: ``Stroustrup``)
-    Like ``Attach``, but break before function definitions.
+    Like ``Attach``, but break before function definitions, and 'else'.
   * ``BS_Allman`` (in configuration: ``Allman``)
     Always break before braces.
   * ``BS_GNU`` (in configuration: ``GNU``)
@@ -213,7 +220,7 @@
 
 **DerivePointerAlignment** (``bool``)
   If ``true``, analyze the formatted file for the most common
-  alignment of & and \*. ``PointerAlignment`` is then used only as fallback.
+  alignment of & and *. ``PointerAlignment`` is then used only as fallback.
 
 **DisableFormat** (``bool``)
   Disables formatting at all.