Find crypto++ under its Gentoo pkg-config name.

dev-libs/crypto++ installs libcryptopp.pc; the SDK asks for libcrypto++.

diff --git a/sdk/cmake/modules/sdklib_libraries.cmake b/sdk/cmake/modules/sdklib_libraries.cmake
index f8b3868..5eb3fb2 100644
--- a/sdk/cmake/modules/sdklib_libraries.cmake
+++ b/sdk/cmake/modules/sdklib_libraries.cmake
@@ -111,7 +111,7 @@ macro(load_sdklib_libraries)
 
         find_package(PkgConfig REQUIRED) # For libraries loaded using pkg-config
 
-        pkg_check_modules(cryptopp REQUIRED IMPORTED_TARGET libcrypto++)
+        pkg_check_modules(cryptopp REQUIRED IMPORTED_TARGET libcryptopp)
         target_link_libraries(SDKlib PUBLIC PkgConfig::cryptopp) # TODO: Private for SDK core
 
         pkg_check_modules(sodium REQUIRED IMPORTED_TARGET libsodium)