lang/openjdk8 build failure on ARM

[Robert Swindells <rjs%fdy2.co.uk@localhost>]

Trying to build lang/openjdk8 on NetBSD/evbarm I get:

Compiling /u4/pkgsrc/lang/openjdk8/work/openjdk/hotspot/src/os_cpu/bsd_zero/vm/os_bsd_zero.cpp
/u4/pkgsrc/lang/openjdk8/work/openjdk/hotspot/src/os_cpu/bsd_zero/vm/os_bsd_zero.cpp: In static member function 'static u_char* os::current_stack_pointer()':
/u4/pkgsrc/lang/openjdk8/work/openjdk/hotspot/src/os_cpu/bsd_zero/vm/os_bsd_zero.cpp:64:10: error: function returns address of local variable [-Werror=return-local-addr]
   return dummy;
          ^
/u4/pkgsrc/lang/openjdk8/work/openjdk/hotspot/src/os_cpu/bsd_zero/vm/os_bsd_zero.cpp:63:11: note: declared here
   address dummy = (address) &dummy;
           ^

Trying to assign the value to a different variable and return that still
gives the same error.