Remove a parameter for file extension from canParse.

canParse took three parameters -- file magic, filename extension and
memory buffer. All but YAMLReader ignored the second parameter.
This patch removes the parameter.

llvm-svn: 234080
diff --git a/lld/lib/ReaderWriter/MachO/MachONormalizedFileBinaryReader.cpp b/lld/lib/ReaderWriter/MachO/MachONormalizedFileBinaryReader.cpp
index ad2d918..b05f431 100644
--- a/lld/lib/ReaderWriter/MachO/MachONormalizedFileBinaryReader.cpp
+++ b/lld/lib/ReaderWriter/MachO/MachONormalizedFileBinaryReader.cpp
@@ -516,14 +516,9 @@
 public:
   MachOObjectReader(MachOLinkingContext &ctx) : _ctx(ctx) {}
 
-  bool canParse(file_magic magic, StringRef ext,
-                const MemoryBuffer &mb) const override {
-    switch (magic) {
-    case llvm::sys::fs::file_magic::macho_object:
-      return (mb.getBufferSize() > 32);
-    default:
-      return false;
-    }
+  bool canParse(file_magic magic, const MemoryBuffer &mb) const override {
+    return (magic == llvm::sys::fs::file_magic::macho_object &&
+            mb.getBufferSize() > 32);
   }
 
   std::error_code
@@ -542,12 +537,11 @@
 public:
   MachODylibReader(MachOLinkingContext &ctx) : _ctx(ctx) {}
 
-  bool canParse(file_magic magic, StringRef ext,
-                const MemoryBuffer &mb) const override {
+  bool canParse(file_magic magic, const MemoryBuffer &mb) const override {
     switch (magic) {
     case llvm::sys::fs::file_magic::macho_dynamically_linked_shared_lib:
     case llvm::sys::fs::file_magic::macho_dynamically_linked_shared_lib_stub:
-      return (mb.getBufferSize() > 32);
+      return mb.getBufferSize() > 32;
     default:
       return false;
     }