Add documentation links for some JNI entities

Add doc page link for:
* AttachCurrentThread call.
* Interface Function Table which describes JNIEnv.

Change-Id: I12b41429c40838e5133e58132930aede287e2e71
Reviewed-by: Alex Blasche <alexander.blasche@qt.io>
(cherry picked from commit d72067c93833e9787a45aeddee800faab0d2d40a)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>

src/corelib/doc/src/external-resources.qdoc

@@ -78,7 +78,7 @@
 
 /*!
     \externalpage https://docs.oracle.com/javase/7/docs/technotes/guides/jni/spec/functions.html
-    \title Oracle: JNI Functions
+    \title Java: JNI Functions
 */
 
 /*!
@@ -90,3 +90,13 @@
     \externalpage https://developer.android.com/training/articles/perf-jni#local-and-global-references
     \title JNI tips: Local and global references
 */
+
+/*!
+    \externalpage https://docs.oracle.com/javase/7/docs/technotes/guides/jni/spec/invocation.html#attach_current_thread
+    \title Java: AttachCurrentThread
+*/
+
+/*!
+    \externalpage https://docs.oracle.com/en/java/javase/13/docs/specs/jni/functions.html#interface-function-table
+    \title Java: Interface Function Table
+*/

src/corelib/kernel/qjnienvironment.cpp

@@ -60,6 +60,8 @@ QT_BEGIN_NAMESPACE
     Since \c JNIEnv doesn't do much error checking, such as exception checking and clearing,
     QJniEnvironment allows you to do that easily.
 
+    For more information about JNIEnv, see \l {Java: Interface Function Table}.
+
     \note This API has been designed and tested for use with Android.
     It has not been tested for other platforms.
 */
@@ -266,7 +268,7 @@ bool QJniEnvironment::registerNativeMethods(const char *className, JNINativeMeth
     In contrast to \l QJniObject, which handles exceptions internally, if you
     make JNI calls directly via \c JNIEnv, you need to clear any potential
     exceptions after the call using this function. For more information about
-    \c JNIEnv calls that can throw an exception, see \l {Oracle: JNI Functions}{JNI Functions}.
+    \c JNIEnv calls that can throw an exception, see \l {Java: JNI Functions}{JNI Functions}.
 
     \return \c true when a pending exception was cleared.
 */
@@ -293,7 +295,7 @@ bool QJniEnvironment::checkAndClearExceptions(QJniEnvironment::OutputMode output
     In contrast to \l QJniObject, which handles exceptions internally, if you
     make JNI calls directly via \c JNIEnv, you need to clear any potential
     exceptions after the call using this function. For more information about
-    \c JNIEnv calls that can throw an exception, see \l {Oracle: JNI Functions}{JNI Functions}.
+    \c JNIEnv calls that can throw an exception, see \l {Java: JNI Functions}{JNI Functions}.
 
     \return \c true when a pending exception was cleared.
 */

src/corelib/kernel/qjniobject.cpp

@@ -160,7 +160,7 @@ QT_BEGIN_NAMESPACE
     \l {JNI Design Overview: Global and Local References}. Local references
     created outside a native method scope must be deleted manually, since
     the garbage collector will not free them automatically because we are using
-    \c AttachCurrentThread. For more information, see
+    \l {Java: AttachCurrentThread}{AttachCurrentThread}. For more information, see
     \l {JNI tips: Local and global references}.
 
     If you want to keep a Java object alive you need to either create a new global