[9] RFR (XS) 8051712 regression Test7107135 crashes

[Chris Plummer]

Hello,

Please review the fix for 8051712:

http://cr.openjdk.java.net/~cjplummer/8051712/webrev.00
https://bugs.openjdk.java.net/browse/JDK-8051712

This fix was already applied to aarch64-port/jdk8, but was missed when 
aarch64-port was integrated into jdk9. This commit is to the jdk9/dev 
mainline, not aarch64-port/jdk9.

The issue is that ElfFile::specifies_noexecstack() assumes that if no 
PT_GNU_STACK record is found, then the platform (loader) defaults to 
execstack. However, for AARCH64 is defaults to noexecstack. More info 
can be found in the following discussion.

http://mail.openjdk.java.net/pipermail/aarch64-port-dev/2014-February/000877.html 


Also see 7107135 for info on the execstack/noexecstack issue, and why 
ElfFile::specifies_noexecstack() exists in the first place:

https://bugs.openjdk.java.net/browse/JDK-7107135

Tested by using JPRT to run the test case on all supported platforms. 
Also ran all default "-testset hotspot" tests on all platforms.

thanks,

Chris