Simplify Boolean expressions

This patch simplifies boolean expressions acorss LLDB. It was generated
using clang-tidy with the following command:

run-clang-tidy.py -checks='-*,readability-simplify-boolean-expr' -format -fix $PWD

Differential revision: https://reviews.llvm.org/D55584

llvm-svn: 349215
diff --git a/lldb/source/Symbol/ObjectFile.cpp b/lldb/source/Symbol/ObjectFile.cpp
index 63b4875..86c18c7 100644
--- a/lldb/source/Symbol/ObjectFile.cpp
+++ b/lldb/source/Symbol/ObjectFile.cpp
@@ -588,9 +588,7 @@
         regex_match.GetMatchAtIndex(path_with_object, 2, obj)) {
       archive_file.SetFile(path, FileSpec::Style::native);
       archive_object.SetCString(obj.c_str());
-      if (must_exist && !FileSystem::Instance().Exists(archive_file))
-        return false;
-      return true;
+      return !(must_exist && !FileSystem::Instance().Exists(archive_file));
     }
   }
   return false;