configure: handle FREETYPE_* variables

This allows the user to set the following variables:
FREETYPE_INCDIR
FREETYPE_LIBDIR
FREETYPE_LIBS

Fixes: QTBUG-72765
Change-Id: Ib70b30f355cc2185c45233e0cfe5e6e55acdf2b6
Reviewed-by: Joerg Bornemann <joerg.bornemann@qt.io>

src/gui/configure.json

@@ -239,7 +239,8 @@
             "sources": [
                 { "type": "pkgConfig", "args": "freetype2" },
                 { "type": "freetype", "libs": "-lfreetype", "condition": "!config.wasm" },
-                { "libs": "-s USE_FREETYPE=1", "condition": "config.wasm" }
+                { "libs": "-s USE_FREETYPE=1", "condition": "config.wasm" },
+                { "libs": "-lfreetype" }
             ],
             "use": [
                 { "lib": "zlib", "condition": "features.system-zlib" }