RFR(S): 8243586: Optimize calls to SystemDictionaryShared::define_shared_package for classpath

[Calvin Cheung]

JBS: https://bugs.openjdk.java.net/browse/JDK-8243586

webrev: http://cr.openjdk.java.net/~ccheung/jdk16/8243586/webrev.00/

The proposed change is to reduce the calls to 
SystemDictionaryShared::define_shared_package which does a java call to 
AppClassLoader.defineOrCheckPackage. Currently, define_shared_package is 
called for every shared class but it is needed only for each package in 
each jar specified in the classpath.

zprint perf results summary:

instr delta = -104380126 -2.2487%
time delta = -23.779 ms -3.3640%

Testing: running mach5 tier1 and 2 tests.

thanks,

Calvin