Solaris: Specify ARCHFLAGS in CFLAGS

Solaris: Specify ARCHFLAGS in CFLAGS

Various autoconf tests which use the C compiler may yield different
results depending on whether or not we are compiling for x86 or amd64
on Solaris (different libraries are available, structures may be
different, et al). So, set CFLAGS depending on which arch we are
targeting, so the autoconf results are more consistent with the actual
compilation during the build.

Reviewed-on: http://gerrit.openafs.org/5786
Reviewed-by: Derrick Brashear <shadow@dementix.org>
Tested-by: Derrick Brashear <shadow@dementix.org>
(cherry picked from commit 5eba97a8960c49aeea957dc94408368e1324eff0)

Change-Id: Idd0f7d2220ae9762af60e96d087e7eb7ee8c0e63
Reviewed-on: http://gerrit.openafs.org/6086
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Derrick Brashear <shadow@dementix.org>