Fix memory leak in unit test of Bitcode/BitReaderTest.cpp

[kschimpf]

Summary

Fixes obvious memory leak in test
TestForEofAfterReadFailureOnDataStreamer. Also removes constexpr use
from same test.

unittests/Bitcode/BitReaderTest.cpp

auto OwnedBytes =
       llvm::make_unique<StreamingMemoryObject>(std::move(Streamer));
   auto Reader = llvm::make_unique<BitstreamReader>(std::move(OwnedBytes));
   BitstreamCursor Cursor;
   Cursor.init(Reader.get());
 
   // Jump to two bytes before end of stream.
   Cursor.JumpToBit((InputSize - 4) * CHAR_BIT);
   // Try to read 4 bytes when only 2 are present, resulting in error value 0.
-  constexpr size_t ReadErrorValue = 0;
+  const size_t ReadErrorValue = 0;
   EXPECT_EQ(ReadErrorValue, Cursor.Read(32));
   // Should be at eof now.
   EXPECT_TRUE(Cursor.AtEndOfStream());
+
+  delete[] Text;
 }
 
 TEST(BitReaderTest, MateralizeForwardRefWithStream) {
   SmallString<1024> Mem;
 
   LLVMContext Context;
   std::unique_ptr<Module> M = getStreamedModuleFromAssembly(
       Context, Mem, "@table = constant i8* blockaddress(@func, %bb)\n"