Only set OPENSSL_DIR for Rust build if it is actually defined

libclamav_rust/CMakeLists.txt

@@ -4,11 +4,18 @@
 # Copyright (C) 2021-2024 Cisco Systems, Inc. and/or its affiliates. All rights reserved.
 #
 
+# if OPENSSL_ROOT_DIR is set, pass it to the environment
+if(OPENSSL_ROOT_DIR)
+    set(ENVIRONMENT "OPENSSL_DIR=${OPENSSL_ROOT_DIR}")
+else ()
+    set(ENVIRONMENT "")
+endif()
+
 # libclamav rust static library
 add_rust_library(TARGET clamav_rust
     SOURCE_DIRECTORY "${CMAKE_CURRENT_SOURCE_DIR}"
     BINARY_DIRECTORY "${CMAKE_BINARY_DIR}"
-    ENVIRONMENT "OPENSSL_DIR=${OPENSSL_ROOT_DIR}"
+    ENVIRONMENT "${ENVIRONMENT}"
     INCLUDE_DIRECTORIES "$<TARGET_PROPERTY:ClamAV::libclamav,INCLUDE_DIRECTORIES>"
     # Tests cannot be pre-compiled here, because there are circular dependencies
     # between libclamav_rust and libclamav to include calls like `cli_getdsig()`