[Courgette] Refactor BSDiff namespaces and bsdiff::search() interface.

courgette/versioning_unittest.cc

Index: courgette/versioning_unittest.cc
diff --git a/courgette/versioning_unittest.cc b/courgette/versioning_unittest.cc
index 3a3a4cbbaa1fc65deea508c306e69cf7d396f458..0257ac46ff597c5b34db8db25342bf658ecb4ca1 100644
--- a/courgette/versioning_unittest.cc
+++ b/courgette/versioning_unittest.cc
@@ -34,10 +34,10 @@ void VersioningTest::TestApplyingOldBsDiffPatch(
 
   courgette::SinkStream generated_stream;
 
-  courgette::BSDiffStatus status = courgette::ApplyBinaryPatch(
+  bsdiff::BSDiffStatus status = bsdiff::ApplyBinaryPatch(
       &old_stream, &patch_stream, &generated_stream);
 
-  EXPECT_EQ(status, courgette::OK);
+  EXPECT_EQ(status, bsdiff::OK);
 
   size_t expected_length = expected_buffer.size();
   size_t generated_length = generated_stream.Length();