Remove the 4GB size check for sample profiles.

[amharc]

Summary

There are legitimate usecases for >4GB profiles and this check doesn't
bring much value.

The counterpart for instrumented profiles has been previously removed in
https://github.com/llvm/llvm-project/commit/d6c15b661ab0aabb00f1219ce4af7136938e67e2.

llvm/include/llvm/ProfileData/SampleProf.h

 namespace llvm {
 
 const std::error_category &sampleprof_category();
 
 enum class sampleprof_error {
   success = 0,
   bad_magic,
   unsupported_version,
-  too_large,
   truncated,
   malformed,
   unrecognized_format,
   unsupported_writing_format,
   truncated_name_table,
   not_implemented,
   counter_overflow,
   ostream_seek_unsupported,

llvm/lib/ProfileData/SampleProf.cpp

std::string message(int IE) const override {
     sampleprof_error E = static_cast<sampleprof_error>(IE);
     switch (E) {
     case sampleprof_error::success:
       return "Success";
     case sampleprof_error::bad_magic:
       return "Invalid sample profile data (bad magic)";
     case sampleprof_error::unsupported_version:
       return "Unsupported sample profile format version";
-    case sampleprof_error::too_large:
-      return "Too much profile data";
     case sampleprof_error::truncated:
       return "Truncated profile data";
     case sampleprof_error::malformed:
       return "Malformed sample profile data";
     case sampleprof_error::unrecognized_format:
       return "Unrecognized sample profile encoding format";
     case sampleprof_error::unsupported_writing_format:
       return "Profile encoding format unsupported for writing operations";

llvm/lib/ProfileData/SampleProfReader.cpp

SampleProfileReaderItaniumRemapper::lookUpNameInProfile(StringRef Fname) {
   return None;
 }
 
 /// Prepare a memory buffer for the contents of \p Filename.
 ///
 /// \returns an error code indicating the status of the buffer.
 static ErrorOr<std::unique_ptr<MemoryBuffer>>
 setupMemoryBuffer(const Twine &Filename) {
-  auto BufferOrErr = MemoryBuffer::getFileOrSTDIN(Filename, /*IsText=*/true);
-  if (std::error_code EC = BufferOrErr.getError())
-    return EC;
-  auto Buffer = std::move(BufferOrErr.get());
-
-  // Check the file.
-  if (uint64_t(Buffer->getBufferSize()) > std::numeric_limits<uint32_t>::max())
-    return sampleprof_error::too_large;
-
-  return std::move(Buffer);
+  return MemoryBuffer::getFileOrSTDIN(Filename, /*IsText=*/true);
 }
 
 /// Create a sample profile reader based on the format of the input file.
 ///
 /// \param Filename The file to open.
 ///
 /// \param C The LLVM context to use to emit diagnostics.
 ///