find_executable(bin, path = nil)
Instance Public methods
Searches for the executable bin on path. The
default path is your PATH environment variable. If that
isn't defined, it will resort to searching /usr/local/bin, /usr/ucb,
/usr/bin and /bin.
If found, it will return the full path, including the executable name, of
where it was found.
Note that this method does not actually affect the generated Makefile.