adding tests

Author: lemire

.github/workflows/s390x.yml

@@ -24,7 +24,7 @@ jobs:
             apt-get update -q -y
             apt-get install -y cmake make g++
           run: |
-            cmake -DCMAKE_BUILD_TYPE=Release -B build
+            cmake -DCMAKE_BUILD_TYPE=Release -B build  -DFASTFLOAT_TEST=ON
             cmake --build build -j=2
             ctest --output-on-failure --test-dir build