Add a feature for Qt Sql

This way we can disable it by passing -no-feature-sql to configure.

Change-Id: Ia47d72101de0788478997fa1854cedcd1742f6fd
Reviewed-by: Lars Knoll <lars.knoll@qt.io>
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@qt.io>

configure.json

@@ -934,6 +934,10 @@
             "label": "Qt Network",
             "output": [ "privateFeature" ]
         },
+        "sql": {
+            "label": "Qt Sql",
+            "output": [ "privateFeature" ]
+        },
         "widgets": {
             "label": "Qt Widgets",
             "condition": "features.gui",
@@ -1128,6 +1132,7 @@ Configure with '-qreal float' to create a build that is binary-compatible with 5
                 "dbus-linked",
                 "gui",
                 "network",
+                "sql",
                 "widgets"
             ]
         }, {

src/src.pro

@@ -124,7 +124,7 @@ src_printsupport.depends = src_corelib src_gui src_widgets src_tools_uic
 
 src_plugins.subdir = $$PWD/plugins
 src_plugins.target = sub-plugins
-src_plugins.depends = src_sql src_xml
+src_plugins.depends = src_xml
 
 src_android.subdir = $$PWD/android
 
@@ -144,11 +144,15 @@ qtConfig(regularexpression):pcre {
 SUBDIRS += src_corelib src_tools_qlalr
 TOOLS = src_tools_moc src_tools_rcc src_tools_qlalr
 win32:SUBDIRS += src_winmain
-SUBDIRS += src_sql src_xml src_testlib
+SUBDIRS += src_xml src_testlib
 qtConfig(network) {
     SUBDIRS += src_network
     src_plugins.depends += src_network
 }
+qtConfig(sql) {
+    SUBDIRS += src_sql
+    src_plugins.depends += src_sql
+}
 qtConfig(dbus) {
     force_dbus_bootstrap|qtConfig(private_tests): \
         SUBDIRS += src_tools_bootstrap_dbus