build: Move lockedpool.cpp from util -> crypto

Allows `crypto` functions and classes to use `secure_allocator`.

src/crypto/CMakeLists.txt

@@ -20,6 +20,7 @@ add_library(bitcoin_crypto STATIC EXCLUDE_FROM_ALL
   sha512.cpp
   siphash.cpp
   ../support/cleanse.cpp
+  ../support/lockedpool.cpp
 )
 
 target_link_libraries(bitcoin_crypto

src/util/CMakeLists.txt

@@ -32,7 +32,6 @@ add_library(bitcoin_util STATIC EXCLUDE_FROM_ALL
   ../random.cpp
   ../randomenv.cpp
   ../streams.cpp
-  ../support/lockedpool.cpp
   ../sync.cpp
 )