Helper function to establish minimal compiler versions, currently limited
only to g++ which (particularly for older RHEL/CentOS releases) is
too far behind current C++11 standards required for some packages.
compilerCheck(minVersion = package_version("4.6.0"))An object of type package_version, with a default
of version 4.6.0
A boolean value is returned, indicating if the minimal version is being met
This function looks up g++ (as well as optional values in the
CXX and CXX1X environment variables) in the PATH. For
all values found, the output of g++ -v is analyzed for the version
string, which is then compared to the given minimal version.