RFR: JDK-8171310: Gtest libjvm.so is always stripped

[Erik Joelsson]

Hello,

Please review this patch, which fixes stripping behavior in the build. 
In JDK-8150736 I reworked the general handling of debug symbols. My 
intention then was to always leave debug symbols in gtest libjvm.so as 
well as all other test binaries. It seems I forgot to set this for gtest 
libjvm.so however.

While investigating this I also discovered that setting 
--with-native-debug-symbols=internal doesn't work. Most binaries are 
stripped anyway. This is a bug in NativeCompilation.gmk. My fix changes 
the default behavior for stripping to only happen if debug symbols are 
also copied.

Since the global defaults are now sane and universal, I also removed all 
explicit STRIP_SYMBOLS:=true settings from specific native libraries. It 
doesn't make sense to strip them if the user asked for internal debug 
symbols and in all other cases they will be stripped anyway.

Bug: https://bugs.openjdk.java.net/browse/JDK-8171310

Webrev: http://cr.openjdk.java.net/~erikj/8171310/webrev.01/

/Erik