[Exim] Fail to build exim 4.12

Please advise why I get the following error message when building exim 4.12,
using gcc 2.95.3, OS Solaris 2.5.1 on Sun Netra:
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In file included from os.c:2:
../src/os.c:372: union has no member named `ui32'
*** Error code 1
make: Fatal error: Command failed for target `os.o'
Current working directory
/kdp4a/user/whelanj/exim4/exim-4.12/build-SunOS5-5.5.1-sparc
*** Error code 1
make: Fatal error: Command failed for target `go'
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John Whelan, Dublin City University,
Glasnevin, Dublin 9, Ireland.
EMAIL: whelanj@???
FAX: +353-1-7005024
PHONE: +353-1-7005364
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