clang-format: Make continuation indent width configurable.

Patch by Kim Gräsman. Thank you!

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@192964 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Format/Format.cpp b/lib/Format/Format.cpp
index ff85767..3496712 100644
--- a/lib/Format/Format.cpp
+++ b/lib/Format/Format.cpp
@@ -163,6 +163,7 @@
                    Style.SpaceAfterControlStatementKeyword);
     IO.mapOptional("SpaceBeforeAssignmentOperators",
                    Style.SpaceBeforeAssignmentOperators);
+    IO.mapOptional("ContinuationIndentWidth", Style.ContinuationIndentWidth);
   }
 };
 }
@@ -214,6 +215,7 @@
   LLVMStyle.SpacesInCStyleCastParentheses = false;
   LLVMStyle.SpaceAfterControlStatementKeyword = true;
   LLVMStyle.SpaceBeforeAssignmentOperators = true;
+  LLVMStyle.ContinuationIndentWidth = 4;
 
   setDefaultPenalties(LLVMStyle);
   LLVMStyle.PenaltyReturnTypeOnItsOwnLine = 60;
@@ -257,6 +259,7 @@
   GoogleStyle.SpacesInCStyleCastParentheses = false;
   GoogleStyle.SpaceAfterControlStatementKeyword = true;
   GoogleStyle.SpaceBeforeAssignmentOperators = true;
+  GoogleStyle.ContinuationIndentWidth = 4;
 
   setDefaultPenalties(GoogleStyle);
   GoogleStyle.PenaltyReturnTypeOnItsOwnLine = 200;