refactor: Drop unused fclose() from BufferedFile

This was only explicitly used in the tests, where it can be replaced by
wrapping the original raw file pointer into a CAutoFile on creation and
then calling CAutoFile::fclose().

Also, it was used in LoadExternalBlockFile(), where it can also be
replaced by the (implicit call to the) CAutoFile destructor after
wrapping the original raw file pointer in a CAutoFile.

src/bench/streams_findbyte.cpp

@@ -4,19 +4,23 @@
 
 #include <bench/bench.h>
 
-#include <util/fs.h>
 #include <streams.h>
+#include <util/fs.h>
+
+#include <cstddef>
+#include <cstdint>
+#include <cstdio>
 
 static void FindByte(benchmark::Bench& bench)
 {
     // Setup
-    FILE* file = fsbridge::fopen("streams_tmp", "w+b");
+    CAutoFile file{fsbridge::fopen("streams_tmp", "w+b"), 0};
     const size_t file_size = 200;
     uint8_t data[file_size] = {0};
     data[file_size-1] = 1;
-    fwrite(&data, sizeof(uint8_t), file_size, file);
-    rewind(file);
-    BufferedFile bf{file, /*nBufSize=*/file_size + 1, /*nRewindIn=*/file_size, 0};
+    file << data;
+    std::rewind(file.Get());
+    BufferedFile bf{file.Get(), /*nBufSize=*/file_size + 1, /*nRewindIn=*/file_size, 0};
 
     bench.run([&] {
         bf.SetPos(0);
@@ -24,7 +28,7 @@ static void FindByte(benchmark::Bench& bench)
     });
 
     // Cleanup
-    bf.fclose();
+    file.fclose();
     fs::remove("streams_tmp");
 }