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/Symbol/ClangASTContext.cpp b/lldb/source/Symbol/ClangASTContext.cpp
index 8184f7c..b5fcc9b 100644
--- a/lldb/source/Symbol/ClangASTContext.cpp
+++ b/lldb/source/Symbol/ClangASTContext.cpp
@@ -1065,7 +1065,7 @@
 }
 
 lldb::BasicType
-ClangASTContext::GetBasicTypeEnumeration(const ConstString &name) {
+ClangASTContext::GetBasicTypeEnumeration(ConstString name) {
   if (name) {
     typedef UniqueCStringMap<lldb::BasicType> TypeNameToBasicTypeMap;
     static TypeNameToBasicTypeMap g_type_map;
@@ -1131,7 +1131,7 @@
 }
 
 CompilerType ClangASTContext::GetBasicType(ASTContext *ast,
-                                           const ConstString &name) {
+                                           ConstString name) {
   if (ast) {
     lldb::BasicType basic_type = ClangASTContext::GetBasicTypeEnumeration(name);
     return ClangASTContext::GetBasicType(ast, basic_type);
@@ -2272,7 +2272,7 @@
 }
 
 CompilerType ClangASTContext::CreateStructForIdentifier(
-    const ConstString &type_name,
+    ConstString type_name,
     const std::initializer_list<std::pair<const char *, CompilerType>>
         &type_fields,
     bool packed) {
@@ -2297,7 +2297,7 @@
 }
 
 CompilerType ClangASTContext::GetOrCreateStructForIdentifier(
-    const ConstString &type_name,
+    ConstString type_name,
     const std::initializer_list<std::pair<const char *, CompilerType>>
         &type_fields,
     bool packed) {
@@ -5739,7 +5739,7 @@
   return num_children;
 }
 
-CompilerType ClangASTContext::GetBuiltinTypeByName(const ConstString &name) {
+CompilerType ClangASTContext::GetBuiltinTypeByName(ConstString name) {
   return GetBasicType(GetBasicTypeEnumeration(name));
 }
 
@@ -5819,7 +5819,7 @@
 void ClangASTContext::ForEachEnumerator(
     lldb::opaque_compiler_type_t type,
     std::function<bool(const CompilerType &integer_type,
-                       const ConstString &name,
+                       ConstString name,
                        const llvm::APSInt &value)> const &callback) {
   const clang::EnumType *enum_type =
       llvm::dyn_cast<clang::EnumType>(GetCanonicalQualType(type));