[NFC] Reordering parameters in getFile and getFileOrSTDIN

In future patches I will be setting the IsText parameter frequently so I will refactor the args to be in the following order. I have removed the FileSize parameter because it is never used.

```
  static ErrorOr<std::unique_ptr<MemoryBuffer>>
  getFile(const Twine &Filename, bool IsText = false,
          bool RequiresNullTerminator = true, bool IsVolatile = false);

  static ErrorOr<std::unique_ptr<MemoryBuffer>>
  getFileOrSTDIN(const Twine &Filename, bool IsText = false,
                 bool RequiresNullTerminator = true);

 static ErrorOr<std::unique_ptr<MB>>
 getFileAux(const Twine &Filename, uint64_t MapSize, uint64_t Offset,
            bool IsText, bool RequiresNullTerminator, bool IsVolatile);

  static ErrorOr<std::unique_ptr<WritableMemoryBuffer>>
  getFile(const Twine &Filename, bool IsVolatile = false);
```

Reviewed By: jhenderson

Differential Revision: https://reviews.llvm.org/D99182

1 files changed, 2 insertions, 1 deletions

diff --git a/llvm/lib/BinaryFormat/Magic.cpp b/llvm/lib/BinaryFormat/Magic.cpp
index 61b1504..591da48 100644
--- a/llvm/lib/BinaryFormat/Magic.cpp
+++ b/llvm/lib/BinaryFormat/Magic.cpp
@@ -223,7 +223,8 @@ file_magic llvm::identify_magic(StringRef Magic) {
 }
 
 std::error_code llvm::identify_magic(const Twine &Path, file_magic &Result) {
-  auto FileOrError = MemoryBuffer::getFile(Path, -1LL, false);
+  auto FileOrError = MemoryBuffer::getFile(Path, /*IsText=*/false,
+                                           /*RequiresNullTerminator=*/false);
   if (!FileOrError)
     return FileOrError.getError();