Check if the given struct or class has the specified member variable

CHECK_STRUCT_HAS_MEMBER(<struct> <member> <header> <variable>
                        [LANGUAGE <language>])
<struct> - the name of the struct or class you are interested in
<member> - the member which existence you want to check
<header> - the header(s) where the prototype should be declared
<variable> - variable to store the result
<language> - the compiler to use (C or CXX)

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_INCLUDES = list of include directories
CMAKE_REQUIRED_LIBRARIES = list of libraries to link

Example: CHECK_STRUCT_HAS_MEMBER(“struct timeval” tv_sec sys/select.h HAVE_TIMEVAL_TV_SEC LANGUAGE C)