Define Darwin definitions for llamacpp

Defines the Darwin build definitions for
llamacpp. This should fix the earlier backwards
compatibility issues.

pkg/lib/harness/generated/gen_darwin.sh

@@ -1,10 +1,12 @@
 set -ex
 set -o pipefail
-echo "Build kit harness for darwin"
+echo "Starting Darwin LLM Harneess build"
 source $(dirname $0)/gen_common.sh
 init_vars
 git_module_setup
 
+COMMON_DARWIN_DEFS="-DCMAKE_OSX_DEPLOYMENT_TARGET=11.3 -DLLAMA_METAL_MACOSX_VERSION_MIN=11.3 -DCMAKE_SYSTEM_NAME=Darwin -DLLAMA_METAL_EMBED_LIBRARY=on"
+
 ## Build devmode UI
 build_ui
 compress ${UI_DIR}/dist ../ui.tar.gz