Version check message does not reflect version checking behavior

In build.sh, check_version() checks if the installed version is greater than the supplied version argument ($2). Then the warning message on failure states that the version needs to at least the value ($2).

Either the warning should state the version needs to be greater than $2 or the comparison check needs to be changed to >= from >.

As is, script will fail with automake version 1.14

```
..../rocket-tools (master)$ ./build.sh
Starting RISC-V Toolchain build process
OpenOCD build requires at least version 1.14 of automake. Aborting.
..../rocket-tools (master)$ automake --version
automake (GNU automake) 1.14
Copyright (C) 2013 Free Software Foundation, Inc.
License GPLv2+: GNU GPL version 2 or later
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.

Written by Tom Tromey
and Alexandre Duret-Lutz .
```