RFR: 8239001: Hotspot build broken on linux-sparc after 8238281

[John Paul Adrian Glaubitz]

Hello!

Hotspot fails to build on linux-sparc after 8238281 due to the redefinition
of offset_of() in src/hotspot/share/prims/jvm.cpp [1]:

/home/glaubitz/jdk/src/hotspot/cpu/sparc/macroAssembler_sparc.hpp: In static member function 'static int RegistersForDebugging::i_offset(int)':
/home/glaubitz/jdk/src/hotspot/cpu/sparc/macroAssembler_sparc.hpp:488:74: error: 'j' cannot appear in a constant-expression
  488 | static int i_offset(int j) { return offset_of(RegistersForDebugging, i[j]); }
      | ^ 

Since offsetof() can only be used with constant expressions, I have reused
the old definition of offset_of() in src/hotspot/cpu/sparc/macroAssembler_sparc.hpp
to fix the issue.

I couldn't come up with a more elegant solution, but I'm open for suggestions.

Please review my change in [2].

Thanks,
Adrian

> [1] https://bugs.openjdk.java.net/browse/JDK-8239001
> [2] http://cr.openjdk.java.net/~glaubitz/8239001/webrev.00/

-- 
 .''`.  John Paul Adrian Glaubitz
: :' :  Debian Developer - glaubitz at debian.org
`. `'   Freie Universitaet Berlin - glaubitz at physik.fu-berlin.de
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