Move RcuVector and relevant support classes to vespalib

Having RCU support available across all our C++ modules open up
new opportunities for optimizations.

This changes the following:
- `RcuVector` moved from `searchlib` to `vespalib`
- `MemoryUsage` moved from `searchlib` to `vespalib`
- Introduce a simplified, more generic `GrowStrategy` in `vespalib`
  used by the moved `RcuVector` which does not have any notion of
  documents. Existing searchlib `GrowStrategy` gets a simple function
  to convert to this generic strategy.

1 files changed, 2 insertions, 2 deletions

diff --git a/searchcore/src/tests/proton/documentdb/document_subdbs/document_subdbs_test.cpp b/searchcore/src/tests/proton/documentdb/document_subdbs/document_subdbs_test.cpp
index a80497636e6..68c388111d3 100644
--- a/searchcore/src/tests/proton/documentdb/document_subdbs/document_subdbs_test.cpp
+++ b/searchcore/src/tests/proton/documentdb/document_subdbs/document_subdbs_test.cpp
@@ -128,8 +128,8 @@ struct MyStoreOnlyConfig
         : _cfg(DocTypeName(DOCTYPE_NAME),
               SUB_NAME,
               BASE_DIR,
-              GrowStrategy(),
-                   0, 0, SubDbType::READY)
+              search::GrowStrategy(),
+              0, 0, SubDbType::READY)
     {
     }
 };