RFR: JDK-8191203 Remove duplicated jimage.hpp

[Magnus Ihse Bursie]

I ran a duplicate name check on the source base. Then I discovered that 
there is a jimage.hpp in both src/hotspot/share/classfile/jimage.hpp and 
src/java.base/share/native/libjimage/jimage.hpp. They are identical 
(apart from copyright headers), and once again, we shouldn't have both. 
David Holmes suggested removing the hotspot version, so this I've done.

I intend to push this to jdk/hs.

Bug: https://bugs.openjdk.java.net/browse/JDK-8191203
WebRev: 
http://cr.openjdk.java.net/~ihse/JDK-8191203-remove-duplicated-jimage-hpp/webrev.01

/Magnus