RFR: 8227631: Adjust AIX version check

[Baesken, Matthias]

Hello, please review this small AIX related change .

For some time, we do not support AIX 5.3 any more.
See (where AIX 7.1 or 7.2 is the supported build platform since OpenJDK11) :

https://wiki.openjdk.java.net/display/Build/Supported+Build+Platforms

The currently used xlc 16.1 (XL C/C++ Compilers) even  needs  minimum  AIX 7.1 to  run , see

http://www-01.ibm.com/support/docview.wss?uid=swg21326972

(and compiling for older releases on 7.1 / 7.2 would not work easily , at least not "out of the box"  to my knowledge .)

So we should adjust the minimum OS version check done in os_aix.cpp in os::Aix::initialize_os_info() .


Additionally the change removes a couple of warnings   [-Wwritable-strings   category]  .

/nightly/jdk/src/hotspot/os/aix/os_aix.cpp:4081:22: warning: ISO C++11 does not allow conversion from string literal to 'char *' [-Wwritable-strings]
    char *name_str = "unknown OS";
                     ^
/nightly/jdk/src/hotspot/os/aix/os_aix.cpp:4089:18: warning: ISO C++11 does not allow conversion from string literal to 'char *' [-Wwritable-strings]
      name_str = "OS/400 (pase)";
                 ^
/nightly/jdk/src/hotspot/os/aix/os_aix.cpp:4100:18: warning: ISO C++11 does not allow conversion from string literal to 'char *' [-Wwritable-strings]
      name_str = "AIX";



Bug/webrev :

https://bugs.openjdk.java.net/browse/JDK-8227631

http://cr.openjdk.java.net/~mbaesken/webrevs/8227631.0/

Thanks, Matthias