util: always include sha1 into the build

util: always include sha1 into the build

SHA1 is now used in all builds when HAVE_SHA1 is defined. Adjust src to
do the same thing, rather than predicating on shader cache.

Fixes: 04e201d0c02 ("mesa: change 'SHADER_SUBST' facility to work with env variables")
Signed-off-by: Ilia Mirkin <imirkin@alum.mit.edu>
Reviewed-by: Dave Airlie <airlied@gmail.com>