Patch to allow us to specify an alternate checkmk script when running tests.

This patch should be sent upstream.

--- check-0.9.14/checkmk/test/check_checkmk.orig	2015-08-06 11:03:07.140153543 -0700
+++ check-0.9.14/checkmk/test/check_checkmk	2015-08-06 11:04:59.521955758 -0700
@@ -39,7 +39,7 @@
     errfname="$outdir/err"
     diffname="$outdir/diff"
     errdiffname="$outdir/err-diff"
-    CHECKMK="$checkmkdir/checkmk"
+    CHECKMK="${CHECKMK_SCRIPT:-$checkmkdir/checkmk}"
     checkmk_cmd='"$CHECKMK" "$infname" > "$outfname" 2>"$errfname"'
 
     rm -f "$outfname" "$errfname" "$diffname" "$errdiffname"