Switch FileHeader.extractFileLines to TemporaryBuffer.Heap

File contents are processed into a single byte[] for character
conversion. The data must fit entirely in memory, so avoid any
file IO.

Change-Id: I3fe8be2e5f37d5ae953596dda1ed3fe6d4f6aebc

org.eclipse.jgit/src/org/eclipse/jgit/patch/FileHeader.java

 		final TemporaryBuffer[] tmp = new TemporaryBuffer[getParentCount() + 1];
 		try {
 			for (int i = 0; i < tmp.length; i++)
-				tmp[i] = new TemporaryBuffer.LocalFile();
+				tmp[i] = new TemporaryBuffer.Heap(Integer.MAX_VALUE);
 			for (final HunkHeader h : getHunks())
 				h.extractFileLines(tmp);
 
 			return r;
 		} catch (IOException ioe) {
 			throw new RuntimeException(JGitText.get().cannotConvertScriptToText, ioe);
-		} finally {
-			for (final TemporaryBuffer b : tmp) {
-				if (b != null)
-					b.destroy();
-			}
 		}
 	}
 

org.eclipse.jgit/src/org/eclipse/jgit/patch/Patch.java

 	}
 
 	private static byte[] readFully(final InputStream is) throws IOException {
-		final TemporaryBuffer b = new TemporaryBuffer.LocalFile();
-		try {
-			b.copy(is);
-			b.close();
-			return b.toByteArray();
-		} finally {
-			b.destroy();
-		}
+		TemporaryBuffer b = new TemporaryBuffer.Heap(Integer.MAX_VALUE);
+		b.copy(is);
+		b.close();
+		return b.toByteArray();
 	}
 
 	/**