Eliminate an unnecessary .c_str()

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@194228 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Frontend/CompilerInvocation.cpp b/lib/Frontend/CompilerInvocation.cpp
index c1999e8..98745ac 100644
--- a/lib/Frontend/CompilerInvocation.cpp
+++ b/lib/Frontend/CompilerInvocation.cpp
@@ -1791,7 +1791,7 @@
     llvm::sys::path::append(systemVersionFile, "Library");
     llvm::sys::path::append(systemVersionFile, "CoreServices");
     llvm::sys::path::append(systemVersionFile, "SystemVersion.plist");
-    if (!llvm::MemoryBuffer::getFile(systemVersionFile.c_str(), buffer)) {
+    if (!llvm::MemoryBuffer::getFile(systemVersionFile.str(), buffer)) {
       code = hash_combine(code, buffer.get()->getBuffer());
 
       struct stat statBuf;