Revert "configure does not print tests option as a default"

This reverts commit d93c4b2307.

Auto is not an option, and does not mean it'll be automatically
detected.
What auto means is that unless explicitly enabled/disabled it'll check
according to the build profile and will enable it automatically if using
the dev profile.

configure.ac

@@ -106,9 +106,9 @@ case "${build_crypto}" in
 esac
 
 AC_ARG_WITH([tests],
-   [AC_HELP_STRING([--with-tests=none|auto|regular|coverage],
-                   [choose testing method: regular, coverage or none or auto(same as regular if profile is dev).
-                    @<:@default=auto@:>@])],
+   [AC_HELP_STRING([--with-tests=none|regular|coverage],
+                   [choose testing method: regular, coverage or none.
+                    @<:@default=none@:>@])],
    [build_tests=${withval}],
    [build_tests=auto])
 
@@ -118,9 +118,6 @@ case "${build_tests}" in
    auto)
      if test "${build_profile}" = "dev"; then
         want_tests="yes"
-        build_tests="regular"
-     else
-        build_tests="none"
      fi
      ;;
    regular)