remove unknown `CPPFLAGS` option

llm/dyn_ext_server.go

@@ -4,7 +4,7 @@ package llm
 #cgo CFLAGS: -I${SRCDIR}/ext_server -I${SRCDIR}/llama.cpp -I${SRCDIR}/llama.cpp/common -I${SRCDIR}/llama.cpp/examples/server
 #cgo CFLAGS: -DNDEBUG -DLLAMA_SERVER_LIBRARY=1 -D_XOPEN_SOURCE=600 -DACCELERATE_NEW_LAPACK -DACCELERATE_LAPACK_ILP64
 #cgo CFLAGS: -Wmissing-noreturn -Wextra -Wcast-qual -Wno-unused-function -Wno-array-bounds
-#cgo CPPFLAGS: -Ofast -Wextra -Wno-unused-function -Wno-unused-variable -Wno-deprecated-declarations -Wno-unused-but-set-variable
+#cgo CPPFLAGS: -Ofast -Wextra -Wno-unused-function -Wno-unused-variable -Wno-deprecated-declarations
 #cgo darwin CFLAGS: -D_DARWIN_C_SOURCE
 #cgo darwin CPPFLAGS:  -DGGML_USE_ACCELERATE
 #cgo darwin CPPFLAGS: -DGGML_USE_METAL -DGGML_METAL_NDEBUG