make more use of 'use' in library detection

now that it works nicely, make use of it for the zlib deps, which are
not transitive when the detected library is built statically.

Change-Id: Iaed87a37b36f714f0b919244cd84809650102ba9
Reviewed-by: Lars Knoll <lars.knoll@qt.io>

src/gui/configure.json

@@ -159,9 +159,10 @@
             "test": "unix/libpng",
             "sources": [
                 { "type": "pkgConfig", "args": "libpng" },
-                { "libs": "-llibpng -lzdll", "condition": "config.msvc" },
-                { "libs": "-lpng -lz", "condition": "!config.msvc" }
-            ]
+                { "libs": "-llibpng", "condition": "config.msvc" },
+                { "libs": "-lpng", "condition": "!config.msvc" }
+            ],
+            "use": "zlib"
         },
         "mirclient": {
             "label": "Mir client libraries",

src/sql/configure.json

@@ -114,8 +114,10 @@
             "test": "unix/sqlite",
             "sources": [
                 { "type": "pkgConfig", "args": "sqlite3" },
-                { "libs": "-lsqlite3", "condition": "config.win32" },
-                { "libs": "-lsqlite3 -lz", "condition": "!config.win32" }
+                "-lsqlite3"
+            ],
+            "use": [
+                { "lib": "zlib", "condition": "!config.win32" }
             ]
         }
     },