Currently libstringPlatformChars is linked with `libjava.so` due to direct references to the following functions in libstringPlatformChars.c. These functions are not standard JNI APIs.

- JNU_GetStringPlatformChars
- JNU_ClassString
- JNU_NewStringPlatform

Same as JDK-8349868, explicitly linking with `libjava.so` causes runtime failure when running the test on static JDK due to missing `libjava.so`. See example failure in https://bugs.openjdk.org/browse/JDK-8349868?focusedId=14751207&page=com.atlassian.jira.plugin.system.issuetabpanels%3Acomment-tabpanel#comment-14751207. libstringPlatformChars is one of the couple rare cases in test/jdk/* that I found so far.