Bug 1592557 - fix prng kat tests, r=jcj

fix for prng kat tests

Differential Revision: https://phabricator.services.mozilla.com/D54095

--HG--
extra : moz-landing-system : lando

tests/gtests/gtests.sh

@@ -24,7 +24,6 @@ gtest_init()
 {
   cd "$(dirname "$1")"
   pwd
-  SOURCE_DIR="$PWD"/../..
   if [ -z "${INIT_SOURCED}" -o "${INIT_SOURCED}" != "TRUE" ]; then
       cd ../common
       . ./init.sh
@@ -100,6 +99,7 @@ gtest_cleanup()
 
 ################## main #################################################
 GTESTS="${GTESTS:-prng_gtest certhigh_gtest certdb_gtest der_gtest pk11_gtest util_gtest freebl_gtest softoken_gtest sysinit_gtest blake2b_gtest smime_gtest mozpkix_gtest}"
+SOURCE_DIR="$PWD"/../..
 gtest_init "$0"
 gtest_start
 gtest_cleanup