fix compare

build-gtest.sh

@@ -24,7 +24,7 @@ case "$OS_NAME" in
 Darwin) 
   mac_os_ver=$(sw_vers -productVersion)
   # Use new Google Test on macOS 11.0 or higher ; old one no longer compiles on 11.0
-  if [[ $(echo "${mac_os_ver} >= 11.0"|bc) -gt 0 ]] ; then
+  if [[ "${mac_os_ver}" >= "11.0.*" ]] ; then
     echo "running on Mac OS 11.0 or higher"
     USE_LATEST_GTEST="true"
   else