have_func(func, headers = nil, opt = "", &b)
Instance Public methods
Returns whether or not the function func can be found in the
common header files, or within any headers that you provide.
If found, a macro is passed as a preprocessor constant to the compiler
using the function name, in uppercase, prepended with HAVE_.
To check functions in an additional library, you need to check that library
first using have_library(). The func shall be
either mere function name or functi