utils: build sha1/disk cache only with Android/Autoconf

Earlier commit imported a SHA1 implementation and relaxed the SHA1 and
disk cache handling, broking the Windows builds.

Restrict things for now until we get to a proper fix.

Fixes: d1efa09d342 "util: import sha1 implementation from OpenBSD"
Signed-off-by: Emil Velikov <emil.velikov@collabora.com>
diff --git a/configure.ac b/configure.ac
index 6b07b2d..de8af87 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1766,6 +1766,7 @@
 fi
 
 
+DEFINES="$DEFINES -DENABLE_SHADER_CACHE"
 AM_CONDITIONAL(NEED_MEGADRIVER, test -n "$DRI_DIRS")
 AM_CONDITIONAL(NEED_LIBMESA, test "x$enable_glx" = xxlib -o \
                                   "x$enable_osmesa" = xyes -o \