[clang-format] Preserve include blocks in ObjC Google style

Summary:
r357567 started to regroup include block for Google style; it was meant to apply
only for C++. This patch reverts this for ObjC.

Reviewers: ioeric

Reviewed By: ioeric

Subscribers: thakis, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D60263

llvm-svn: 357695
diff --git a/clang/lib/Format/Format.cpp b/clang/lib/Format/Format.cpp
index 49977b6..8d86be5 100644
--- a/clang/lib/Format/Format.cpp
+++ b/clang/lib/Format/Format.cpp
@@ -877,6 +877,11 @@
   } else if (Language == FormatStyle::LK_ObjC) {
     GoogleStyle.AlwaysBreakBeforeMultilineStrings = false;
     GoogleStyle.ColumnLimit = 100;
+    // "Regroup" doesn't work well for ObjC yet (main header heuristic,
+    // relationship between ObjC standard library headers and other heades,
+    // #imports, etc.)
+    GoogleStyle.IncludeStyle.IncludeBlocks =
+        tooling::IncludeStyle::IBS_Preserve;
   }
 
   return GoogleStyle;