CheckLibraryExists

Check if the function exists.

CHECK_LIBRARY_EXISTS (LIBRARY FUNCTION LOCATION VARIABLE)

LIBRARY  - the name of the library you are looking for
FUNCTION - the name of the function
LOCATION - location where the library should be found
VARIABLE - variable to store the result
           Will be created as an internal cache variable.

The following variables may be set before calling this macro to modify the way the check is run:

CMAKE_REQUIRED_FLAGS = string of compile command line flags
CMAKE_REQUIRED_DEFINITIONS = list of macros to define (-DFOO=bar)
CMAKE_REQUIRED_LIBRARIES = list of libraries to link
CMAKE_REQUIRED_QUIET = execute quietly without messages