Pass ConstString by value (NFC)

My apologies for the large patch. With the exception of ConstString.h
itself it was entirely produced by sed.

ConstString has exactly one const char * data member, so passing a
ConstString by reference is not any more efficient than copying it by
value. In both cases a single pointer is passed. But passing it by
value makes it harder to accidentally return the address of a local
object.

(This fixes rdar://problem/48640859 for the Apple folks)

Differential Revision: https://reviews.llvm.org/D59030

llvm-svn: 355553
diff --git a/lldb/source/Plugins/Language/CPlusPlus/BlockPointer.cpp b/lldb/source/Plugins/Language/CPlusPlus/BlockPointer.cpp
index 6086aff..87b5b59 100644
--- a/lldb/source/Plugins/Language/CPlusPlus/BlockPointer.cpp
+++ b/lldb/source/Plugins/Language/CPlusPlus/BlockPointer.cpp
@@ -149,7 +149,7 @@
   // maybe return false if the block pointer is, say, null
   bool MightHaveChildren() override { return true; }
 
-  size_t GetIndexOfChildWithName(const ConstString &name) override {
+  size_t GetIndexOfChildWithName(ConstString name) override {
     if (!m_block_struct_type.IsValid())
       return UINT32_MAX;