clang-format: Break before 'else' in Stroustrup style.

Seems to be the desired thing to do according to:
  http://www.stroustrup.com/Programming/PPP-style-rev3.pdf

Patch by Jarkko Hietaniemi, thank you!

llvm-svn: 214857
diff --git a/clang/unittests/Format/FormatTest.cpp b/clang/unittests/Format/FormatTest.cpp
index 8089b3e..e0841ca 100644
--- a/clang/unittests/Format/FormatTest.cpp
+++ b/clang/unittests/Format/FormatTest.cpp
@@ -7677,6 +7677,17 @@
                "}",
                BreakBeforeBrace);
 
+  verifyFormat("void foo()\n"
+               "{\n"
+               "  if (a) {\n"
+               "    a();\n"
+               "  }\n"
+               "  else {\n"
+               "    b();\n"
+               "  }\n"
+               "}\n",
+               BreakBeforeBrace);
+
   verifyFormat("#ifdef _DEBUG\n"
                "int foo(int i = 0)\n"
                "#else\n"