add (lib)attr and libacl as optional libraries

when libacl is built and --enable-fpm is used, also enable --with-fpm-acl

config/lib.json

@@ -24,6 +24,12 @@
             "pkg-config"
         ]
     },
+    "attr": {
+        "source": "attr",
+        "static-libs-unix": [
+            "libattr.a"
+        ]
+    },
     "brotli": {
         "source": "brotli",
         "static-libs-unix": [
@@ -234,6 +240,15 @@
             "libsodium"
         ]
     },
+    "libacl": {
+        "source": "libacl",
+        "static-libs-unix": [
+            "libacl.a"
+        ],
+        "lib-depends": [
+            "attr"
+        ]
+    },
     "libaom": {
         "source": "libaom",
         "static-libs-unix": [