8033372: Check jdk/src/share/native/java/lang for JNI pending exception issues

[Alan Bateman]

There are a number of places in the native methods where there are 
sequences of JNI calls and where we don't check for errors or pending 
exceptions. This patch fixes up a number of these issues in the 
java.lang native code, and one remaining one in the java.io native code 
that may have been missed by previous clean-up in this area.

The changes are trivial and the webrev is here:

http://cr.openjdk.java.net/~alanb/8033372/webrev/

Thanks,

Alan.